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As you may or may not have noticed, we have updated our website to a much nicer and faster website template! There’s still a few minor kinks to work out (such as images in product pages being too large) but we’ll get to them all eventually. Hopefully this new template will help make navigating our site faster and easier! Please reply with any comments you might have 
In association with MySubie.com, we are indeed having a BBQ this year, albeit a relatively small one 
Robert and the guys from MySubie.com are coming into town and we’ve arranged to have a little BBQ and meet during the limited amount of time that they’ll be here. They really want to meet some fellow Subaru folk while they’re in the area, so please come on down and enjoy some BBQ goodness! We’re well aware that not everyone would be able to make it down on a MUNday night, but this was the only time available for the MySubie.com guys.
We will be providing some burgers and hot dogs out of the back of our shop where the grill is located, but you’re more than welcome to bring chips, soda, and perhaps more items to grill if you like. Weather-depending, we might be able to take some photos behind the shop as well. All photos of course will be featured on the World One Performance Blog. I know that Robert had mentioned doing some sort of after BBQ cruise of sorts, but we’ll probably play that by ear. Robert even has this even listed here:
http://www.mysubie.com/event/Case-of…Performance/78
Please post on here if you plan to attend or if you have any questions 
Hope to see you then!
EVENT DETAILS:
Where: World One Performance, 20620 84th Avenue South Kent, WA 98032
When: MUNday, August 31st @ 6 pm to 9 pm
What to Bring: Yourself, your family, your friends, your Subaru, your appetite, and any other food you’d be willing to share
Please drive around to the back of the shop, since this BBQ is being held after normal business hours
In its fourth year coming to the greater Seattle area, Formula D returned stronger and more exciting than ever this past Saturday, August 8th. I’ve been covering Formula D for Subiesport/DrivingSports each year it’s come to Seattle, and I honestly do believe it gets better and better every year. In past years, I’ve endured scorching heat (100+ temps on the track) and pouring rain, but this year the overcast weather held up nice and dry, without being too hot or too cold. While the weather conditions seemed ideal all around, the newly redone track surface proved to be challenging for most of the drivers this year, resulting in more crashes, injuries, and broken cars than any of the past 3 years. Dai Yoshihara had a mechanical failure in his Lexus IS350 in practice that resulted in him slamming into the wall right at the first break and he had to be taken to the hospital with a mild concussion. Other cars lost front and/or rear bumpers, Ken Gushi’s Scion tC broke a driveshaft, and even the Pro-Am racers preceding the Top 16 raced fender-less and with duct-taped hoods. All of this action continued to wow the packed grandstands and paddock, to which the Formula D officials always mention as being among the best crowds throughout the entire tour. Ultimately, Chris Forsberg in the NOS Energy / Maxxis Tires Nissan 350Z went on to win the event and widen his points lead for the Formula D 2009 Championship.
Being among the crowd and the media, it was clear to me that Formula D could be seen as a saving grace for the import car enthusiast scene in the greater Seattle area, or perhaps even the entire Pacific Northwest, including British Columbia. With Battle of the Imports not coming to the Seattle area this year and all of the major import car shows canceling their Seattle and Vancouver BC shows this year as well, the import car enthusiasts in this area very much need an event like Formula D. I believe that given the sheer numbers and enthusiasm of the crowd, many of these people would agree with me. Those of us who live in this are can only hope that more events such as this will pay visit to the greater Seattle area next year.
Click here to view the entire gallery on Armin H. Ausejo’s SmugMug.
Tomorrow, I’ll be at Formula D Seattle not only participating in the car show, but also taking photos on track for Subiesport Magazine and DrivingSports.com. I’ll be sure to share a few photos here, but you’ll most likely be able to view them on DrivingSports.com once processing and uploading is finished. To the left, you see me still holding down the shutter on the camera while the AE86 loses control and drifts toward the barrier…lucky for me, he came to a stop right before hitting it, but I was still pretty scared. Hopefully it won’t rain like it did last year! Until then, please feel free to browse my past Formula D Seattle photos at these links below:
Continuing from the other day’s blog, you can see we’re obviously a day behind. But, let’s continue without delay!
The UTEC quickly became the go-to form of engine management between 2003 and 2004, but soon Cobb released their own AccessPort to compete with the UTEC. The AccessPort was a reflashing device instead of a piggyback ECU, which offered several advantages. Being a reflashing device, nothing needed to be installed between the stock ECU and the car (like how piggybacks are installed), and since it reflashed the stock ECU, it was similar to the ECUtek in terms of tuning resolution. Since this reflashing was done through the car’s OBD-II port under the steering wheel, the AccessPort could also be used to log and/or display types of data, such as RPM, throttle position, and more. The AccessPort also included pre-made basemaps for specific engine mods, which made it just as easy, if not easier to use, than the UTEC for those who are not interested in doing their own tuning. Cobb eventually released their own AccessTuner to allow users to do their own tuning, but it was a separate option and not included as part of the standard AccessPort package. For those who didn’t care to tune their own car, Cobb gave their dealers with AWD dynos the option to do “Protunes,” which allowed for professional tuning via the AccessPort at a shop. These Protunes could also be saved and distributed, so many Protuners released their own maps to match specific modifications as well. Despite some initial hiccups to get all of the basemaps working properly and safely for all vehicles, the AccessPort went on to become a huge success for Cobb Tuning, and it eventually overthrew the UTEC for the king of the hill in affordable engine management.
However, the basemaps that both TurboXS and Cobb supplied did have their disadvantages. In order to maintain safety, these maps were tuned for the lowest common denominator and were specific per octane level as well, to ensure that customers would not blow up their motors. While they still improved performance over being untuned and they kept the motor healthy, there was still always going to be room for improvement with a custom tune for each specific car. This still remains true today, although the margin for improvement has been able to shrink with some new engine management options available. The other problem (although not a problem for most people) is that you typically have to follow a specific mod path for the basemaps, and if you stray away from that, you have to get a custom tune for your car no matter what. While for big horsepower applications a custom map is a given, simply changing your intake away from the stock airbox is enough to warrant a custom tune, except for intakes specifically developed by TurboXS and Cobb Tuning respectively. As mentioned in the previous blog, the stock airbox is rather efficient so this may not be a big deal, but not being able to change the intake without a custom tune does put limits on your freedom of modification. Striving for more freedom of modification, other companies sought out to create another option for those people who wanted to not only wanted more freedom than he UTEC and AccessPort offered, but also get away from the limits of the stock ECU itself.
Enter the Element Tuning Hydra EMS. In 2005, Element Tuning entered the fray with their version of the Hydra EMS. The Hydra is a standalone ECU that completely replaces the stock unit. While standalone ECUs of the past required the user to tune every aspect of the car’s behavior from simply idling all the way up to wide-open throttle, Element Tuning took this difficult and time-consuming process out of the equation by taking care of all this programming already, as well as shipping the Hydra with basemaps specific to each car’s modifications, much like the UTEC and AccessPort. Moreover, Element also had maps available for a wide variety of different sized turbos, water/alcohol injection, and different sized intercoolers and intakes. The Hydra also had equal or better tuning resolution than the stock ECU, thus a basemap from a Hydra would typically be more accurate than that of a UTEC or AccessPort. This lowered the amount of custom tuning that would need to be done, but of course a custom tune per vehicle would also bring out the full potential of the car’s setup, which of course was easily possible with the provided software. On top of all this, the Hydra was also very adaptable to different environmental conditions, so the problem of having a map tuned for sea level and then needing a completely different map for mountain passes was effectively eliminated. Our own World One STI back in 2004 actually had a prototype Hydra EMS that helped it finish 2nd in its class and 6th place overall at the very first Primedia Time Attack. However, as good as this system is for tuning and adaptability, it also had its disadvantages, especially for daily drivers. The main issue is that because it’s a replacement to the stock ECU, it does not support OBD-II, and thus it will not pass emissions in just about every state in the country. The other issue, although it may be a very minor issue to some, is that you also lose your cruise control, however this is problem is apparently being fixed for the 08-09 STI. AEM soon followed up with their own plug-n-play Hydra EMS, but not until just in the past year, so support and available tuners aren’t quite as available at this time currently.
Since the release of the Hydra, both TurboXS and Cobb Tuning have updated their UTECs and AccessPorts respectively to add more features, but yet another option was introduced in 2006 that has since thrown the engine management market on its head. A group of computer-minded enthusiasts put their minds together and were able to connect to the stock ECU and then go on to start programming it. It took awhile to get things reliable and easier to use, but as it stands today, this Open Source style of tuning using the OpenECU software has become an easy entry point for customers to start tuning their own vehicles, especially since the software itself is free to download. The only purchase necessary is the Tactrix cable, that allows you to connect your laptop to your car’s OBD-II port (much like how the AccessPort connects). While OpenECU is always in a state of development, many tuners have embraced the software and use it as their primary form of tuning, allowing them to tune to the same levels as that of the AccessPort and ECUtek. Of course, the drawback is that you have to rely on user support rather than having any guarantees or formal support from a company, so in many cases, you’re on your own.
Overall, Subaru owners should be thankful that they have so many choices available to them. This isn’t the case with other makes such as Mitsubishi and Nissan. No matter what form of engine management you choose, it’s always important to understand that how well your car performs is going to depend on how the car is tuned, whether that’s strictly from a basemap or from a custom tune. If you go with a custom tune, be sure the you go to a reputable tuner that has experience tuning the type of setup that you have. After all, just because someone can tune a 300 whp car doesn’t mean that they won’t have any problems tuning a 600 whp car. As always, if you have any questions, please feel free to contact us or post a comment here. For our next part in this series, we’ll be talking about intercoolers, both top mount and front mount, and how they can affect your car’s behavior.
Last week, we finished discussing the different downpipe options out there, but before we get started with intakes and engine management, I just want to make note of the title change of this particular blog series. The reason for this is that it was mentioned to me by a reader (thanks, Mike!) that this same advice will also apply to Legacy GT and Forester XT owners as well. While some of the designs of the exhaust components may be different, the motors all behave similarly since they’re almost exactly the same anyway. Thus, if you’re a Legacy GT and/or Forester XT owner, don’t fret: these same mods will work for you too!
Anyway, we’ve covered the turboback portion of the exhaust, so now let’s talk about the intake. Just like with some of the exhaust myths we previously discussed, the intake has many myths associated with it as well. Some people have insisted that any and all aftermarket intakes are bad for your car, and that your car will soon near explode if one is installed. This blatant generalization is really quite false, and while some aftermarket intakes do not work as well or are as properly-designed as others, putting on an aftermarket intake is not going to spell instant death for your Subaru. In fact, it was proven in the November 2008 issue of Subiesport Magazine that intakes do make a difference, and that certain intakes are definitely better than others, especially after tuning. Thus, if you’re afraid that getting an intake is going to hurt your car, as long as you choose wisely, everything should work out just fine. While the stock airbox is actually very efficient and is already by design technically a cold air intake, an aftermarket intake will provide a noticeable increase in throttle response, since the higher flow of air will help your engine rev faster. This higher flow of air however can pose some problems, especially the farther along you go in your power mod path.
These problems arise when choosing your engine management options. Unlike other cars, such as the Evo, the stock Subaru ECU (or “engine control unit”) can be very temper-mental, depending on the mods you put on the car before tuning. Just like how the myth propagated that an aftermarket intake will blow up your car, a similar myth has been attributed to the turboback exhaust system, with some claims that installing a turboback will void your warranty. This is absolutely not the case, and we’ve even fought a local Subaru dealership and won in a warranty fight, with Subaru of America themselves ordering the dealership to provide warranty service to our customer’s car. In any case, this “if you install this mod, you’ll blow up your car” nonsense ties in to engine management, since now the phrase has become “if you install this mod, you’ll blow up your car UNLESS you get some engine management.” The truth is, YES, your car will perform better when tuned properly with good engine management, and YES your car will be more reliable and safer when tuned properly with good engine management, but NO your car will NOT blow up just because you installed an aftermarket intake and an aftermarket turboback exhaust system. Obviously, this doesn’t take a person’s driving style into account, but the whole idea of instantaneous motor death is ridiculous at best. We still very much recommend engine management at this point, but more because it’ll truly bring out the full potential of the car (especially when tuned properly) and because the car will perform better and more reliably, but not because it casts some sort of protection charm over you motor.
So, if engine management isn’t absolutely and completely necessary at this point, at what point is it? The intake and turboback modifications we’ve discussed are still really basic bolt-ons, thus the temper-mental stock ECU can still do its job without too many problems. However, the additional airflow both into the motor and out of the motor does confuse the stock ECU a bit, hence why engine management at this point is definitely recommended to get the ECU back on the right path. Beyond this point, when you add even more air flow (such as a bigger turbo, intercooler, and intake) and also more fuel (such as larger fuel injectors), the stock ECU simply does not know what to do, and thus engine management is absolutely necessary. Often times, the car simply will not idle or run at all without engine management and these additional mods. Thus, to put it plainly: for an intake and turboback, you’ll probably be just fine, but for anything more than that, you’ll definitely want engine management.
Now that you found a need for engine management, either because you’re going with big power mods or because you just want your turboback to perform to its fullest potential, what’s the best engine management choice? This is where things could potentially get complicated. There are three main forms of engine management available for Subarus:
ECU Reflash
Piggyback ECU
Standalone ECU
While each of these forms of engine management accomplish the same basic principles, they each do it in different ways, and ultimately to different levels of success as well. An ECU Reflash uses the stock ECU, but loads different maps on it to control the motor, allowing the stock ECU to still control other functions such as the HVAC and cruise control. Piggyback ECUs are small computer devices that act as a middle man between the stock ECU and the rest of the car, with one end plugged into the stock ECU and the other end plugged into the car’s wiring harness. Finally, standalone ECUs completely replace the stock ECU with a new one.
Back when the WRX first made its way across the Pacific in 2001, the two main engine management solutions available at the time specifically for the WRX were the ECUtek reflash and the Dastek Unichip, which was offered by TurboXS and Vishnu Performance. The ECUtek reflash worked and still works well, but the license to be an ECUtek programmer was/is on the very expensive side, so typically these reflashes needed to be performed by a shop every time. The TurboXS and Vishnu Unichips on the other hand had a pre-installed basemap to suit specific level of car modification right out of the box, and could be further programmed by an authorized tuning shop specifically for each vehicle. The difference between the different company’s Unichips was how the basemaps were programmed and how they would connect to the car, either via a wiring harness or if they had to be hard-wired. It was from TurboXS’s “Stages” that we get the Stage 1 to 4 levels that we still use to this day: Stage 1 was for a Unichip and catback only, Stage 2 was for a Unichip and Turboback, Stage 3 was for an added larger intercooler, and Stage 4 was for an added larger turbo, injectors, and fuel pump. Anything more than that was simply considered “Stage 4+”. Since both Unichips came with a preloaded map to match your level of modification and it was a relatively easy install, the Unichip was by far the more popular option at the time. However, one problem with these preloaded basemaps is that they were designed specifically for the airflow of only the stock intake airbox, and thus aftermarket intakes were not compatible with the preloaded basemaps, and therefore required custom tuning. This caveat has been an issue with many later forms of engine management, including the Cobb Tuning AccessPort we all know and love today. Nevertheless, people (myself included) happily removed the aftermarket intake they purchased and reinstalled the stock airbox to ensure that the Unichip was happy and performing properly. Standalone ECUs such as the Tec 3, LinkECU, and MoTec existed, but since they did not have the same plug-n-play functionality of the Unichip, they were often only used by more hardcore WRX modifiers. After all, the last thing most customers want to do is spend hours tuning their ECU just to get their car to idle correctly, let alone actually increase performance over stock.
Over time, the Unichip started to show some problems. For one thing, certain Unichip owners would find that the pre-loaded basemap on their Unichip would either simply be erased over time, or the stock ECU would actually override the Unichip, rendering it completely useless. The Unichip’s tuning resolution (the actual increments and scale of tuning certain things such as air/fuel ratio and ignition timing at specific RPM) was also nowhere near that of the ECUtek, so even the custom tunes did not end being as good as they could have been with better resolution. Given the problems they were having, TurboXS went on to develop and release the User-Tunable Engine Computer, or “UTEC.” The UTEC was a big step forward in not only tuning resolution, but because it allowed the user themselves to actually tune their car, rather than requiring a shop to tune it for them. TurboXS still provided basemaps to start from, and the user could load them onto their UTEC via laptop or taking the UTEC out of their car and plugging it into their home computer. This opened up a world of possibilities for many people, some of which are now prominent tuners who first started out tuning on the UTEC. Vishnu attempted to answer TurboXS’s ante with their own “XEDE,” but the XEDE proved to not be quite as versatile or as easy to use as TurboXS UTEC, and soon Vishnu abandoned Subarus and moved on to the brand new Evo market (which they also eventually abandoned).
See as this blog is starting to get quite lengthy, we will conclude this discussion on engine management in tomorrow’s blog.
Although not brand-spanking new, the StopTech Trophy-series Big Brake Kits are already starting to make a name for themselves in the motorsports world. here’s a short description from the StopTech/Centric press release:
These racetrack and competition brake systems come with StopTech’s new Trophy STR lightweight forged calipers in four- or six-piston configurations and include the option of a quick release version of the StopTech patented bridge. These “track only” calipers feature the same metallurgy and design of the StopTech ST-40 and ST-60 calipers, but are engineered to provide a 20-percent reduction in weight without sacrificing stiffness or performance…
StopTech Trophy Big Brake Kits include the company’s patented AeroRotors, engineered to increase airflow by 11 percent for better cooling and performance. Unique to the Trophy Brake Systems is full-floating mounting hardware, which eliminates pad knock-back. The patented, billet 7075 aluminum AeroHats create an additional 4 percent airflow. Together, these technologies optimize the rotor system to provide even performance and consistent feedback to the pedal under the unique combination of hard cornering and braking found on the track.The StopTech Trophy calipers and AeroHats use an exclusive, high-temperature “natural” finish that combines with the AeroRotor for an attractive and attention getting in-wheel presentation. The kits also include billet aluminum mounting brackets with stainless steel caliper studs and DOT-compliant stainless steel braided brake lines. All StopTech Big Brake Kits provide larger rotors that increase heat capacity and dissipation coupled with stiffer calipers and stainless steel lines that reduce system compliance. The results are shorter stopping distances, better brake modulation, firmer pedal feel and less brake fade, resulting in stronger, more reliable performance.StopTech Trophy Brake Systems will be available through motorsports distributors in January 2009 for selected high-performance production cars including Porsche, BMW, Mitsubishi Lancer EVO, Nissan GTR and 350Z, Chevrolet Corvette C5 and C6 and others. StopTech will premiere the Trophy Brake Systems at the Performance Racing Industry Show in Florida this month at booth 3958.
Last Saturday, we travel with Erich 2 – 2 1/2 hours east on I-90 to shoot his car for an upcoming publication. The original areas we had in mind to shoot turned out to be extremely busy, thanks in part to the 90-100 degree temperatures that were predicted. However, after driving along for a bit, we found a scenic view that worked perfectly for our needs. Here are just three of the photos we took at this location:
And the view from the actual location in Vantage, WA. The bridge you see is actually I-90 crossing the Columbia River:
Right now, we’re just waiting on confirmation from the publication to get these photos in.
It’s always good to see a solid wheel company release new designs, despite how well their current designs are doing. Volk’s G-series of 1-piece forged wheels is a welcome addition to the Volk Racing catalog, especially since the light-weight and ultra-strong 1-piece wheels were only limited to 4 different styles for over a year now, with only color variations being the only difference. The Volk Racing G2 was the first of the G-series to be announced, and being a TE37-lover myself, this new 6-spoke, 1-piece forged wheel has me drooling. Available colors are Formula Silver:
and Flat Black:
Currently, these wheels are only available in 19-inch and 20-inch sizes, but here are a few fitments of interest:
For 08-09 STI: 19×8.5 +35, 19×8.5 +43 5×114.3, 19×9.5 +45 5×114.3
For Evo X: 19×8.5 +35, 19×9.5 +35, 19×9.5 +23 (very aggressive)
For 350Z/G35 Coupe: 19×9.5 +23, 19×10.5 +22
For 370Z: 19×9.5 +42, 19×10.5 +22
For G37 Coupe: 19×9.5 +35, 19×9.5 +45, 19×10.5 +35
For E46 M3: 19×8.5 +35, 19×9.5 +22, 19×10.5 +25
For E90 3-series: 19×8.5 +35, 19×9.5 +35
For E92 M3: 19×9.5 +22, 19×10.5 +25
There are a few wheels in stock on our side of the Pacific, but we can always special order a set if needed. Here’s a few sample photos on cars:
Yesterday, we discussed the choosing of an aftermarket catback system to the WRX or STI, not only for additional power, but also for aesthetic purposes. However, as much as we all love the boxer sound, in terms of actual measurable power, the catback alone really doesn’t do much. Thus, after the catback, the next power mod most people consider is an aftermarket downpipe. The downpipe is where the true power starts to be made, since as you can see from the photo to the right, the stock downpipe has 2 power-robbing catalytic converters, or “cats” for short. In this photo, the downpipe on the bottom is the stock downpipe, whereas the downpipe on the top is an Invidia catless downpipe. In comparing the two downpipes, you’ll also notice a few differences other than the cats: the stock downpipe is split into two pieces (some people and manufacturers only refer to the top-most section as the downpipe, and the second section as the midpipe), and the flange at the top that connects to your turbo has a flat plate. These two differences are clear examples of how different companies prefer to approach creating an aftermarket downpipe.
Before we go further however, we must make a disclaimer: removal of the stock catalytic converters is for off-road use only, and if caught using a catless system on the street, you may be cited and fined. In other words, you do have to pay to play, so make sure you’re well aware of this, especially in states like California where emissions laws are very strict and may involve impounding your car if violated. Now that that’s out of the way, most aftermarket downpipes have the following features that are geared as improvements over the stock downpipe:
Of course, just the same as with catbacks, not every downpipe is equal, and this is even more clear with the different designs out there. No matter the design though, the main thing that really should be considered is fitment. Some downpipe have problems fitting due to hanger location, but others simply have issues with fitting because they’re made to mate to their own proprietary exhaust system, so they might require a separate pipe for it to connect to the aftermarket catback of your choice. On top of this, most aftermarket downpipes will not bolt on directly to the stock catback for 02-07 WRXs and STIs, however this is completely the opposite for 08-09 WRXs and STIs, which don’t have any problem bolting to the stock catback. Why would you want to bolt onto the stock catback you might ask? Well, although you do sacrifice power by sticking with the stock catback (since it creates a bottleneck), you do get a significant power increase over stock and you don’t attract any unneeded attention from the authorities.
Once you’ve sorted out fitment issues, the next thing to consider is going catless or staying green-friendly with a high-flow cat. It has been argued that a good high-flow cat will not hamper power at levels below 400 whp, but in our experience, this has not been the case whatsoever. Moreover, running catless helps with throttle response and faster turbo spool since there’s no back pressure in the exhaust system to slow down the exhaust flow. It has also been argued that running catless creates a bad exhaust smell in the cabin, but while this may be the case when a catless downpipe is initially installed, the smell does go away over time, so long as the downpipe was installed properly with no leaks. And, since catted downpipes are typically almost twice as expensive as catless downpipes, unless you absolutely need a catted downpipe for emissions or racing restrictions, we always recommend a catless downpipe. Catless? But what about the check engine light? Well, certain forms of engine management will turn off this check engine light for you, but we will get into that when we talk about engine management in a future part of this blog series.
After deciding on whether to go catless or catted, the next big decision is in regards to the downpipe’s flange at the turbo side. Here are a few examples of the available options, other than stock downpipe’s flat plate design. First up is the “bellmouth” design, which looks like this on the TiTek downpipe:
Next up are two variations of the “divorced wastegate” design. The idea behind the divorced wastegate is that a stock style turbo has exhaust gases the escape from the turbo’s internal wastegate, and since that might cause turbulence when mixed in with the ordinary exhaust gases that exit the turbo, it’s better for these gases to exit out separately so that the exhaust flow is not interrupted. The first one is Invidia’s version, which is essentially just a flat divider plate that diverts the gases, but the gases still go down the same exact pipe further along:
In contrast, here is Element Tuning’s take on the divorced wastegate design. This downpipe actually features a completely separate pipe for the wastegate gases, which then meets up later on with the rest of the piping. The theory behind this is that it’s a true divorced wastegate and the extra smaller piping creates a venturi effect which makes the wastegate gases not only flow faster, but also create a suction effect that makes the rest of the exhaust gases flow faster as well:
In our experience, we definitely recommend either of the above styles. It’s best to stay away from the stock downpipe’s flat plate style, which can be found on a few downpipe brands out there. However, between a bellmouth and Invidia’s divorced wastegate style, we have not seen or felt a significant difference in power. On the other hand, Element Tuning’s divorced wastegate style has proven to produce more power over the other styles.
Finally, you’ll notice that Element Tuning’s downpipe is a 2-piece design, whereas the Invidia design is a 1-piece. Generally speaking, a 1-piece tends to be better when avoid exhaust leaks, but a 2-piece design gives the option to change from a catless race pipe to a catted pipe at your discretion. Not every 2-piece downpipe has an option for a catted downpipe however, so it’s best to do your research (as always) before purchasing. Nevertheless, if you have any further questions, again please don’t hesitate to contact us. For the next blogs, we’ll change gears a little bit and highlight some products and feature a customer car, but next week we’ll come back to the power mod path with a discussion about intakes and engine management.