World One Performance Blog

Undoubtedly, one of the most popular inquiries we receive from new WRX or STI owners who have been bitten by the mod bug is, “how do I get more power out of this car?” Ever since the first original 2002 WRX commercials back in 2001, people have always bought this car to go fast, and with the right combination of modifications, going fast is relatively easy. In the next series of blogs, we’ll be strictly discussing power modifications, all the way from the basics to more power than you’ll likely ever truly use in the lifetime of your car. Although the vast majority of these modifications are bolt-ons, there’s always going to be some pros and cons to each mod, whether it be in driving characteristics or simply not being street legal. We will definitely discuss these pros and cons as we go along and we will make it a goal to make this discussion easy enough to understand for someone who is completely new to cars, let alone Subarus in particular.

Before we jump into the thick of things, it’s important to remember that while there’s a lot of different “Stage” numbers being thrown around, these stages are not universal. Back in 2002, TurboXS came out with their own “Stage 1-4,” and then later Cobb Tuning came out with their own “Stage 1 and 2,” but there really hasn’t ever been an officially agreed upon requirement of certain mods to reach a specific “Stage.” We will however mention what unofficial “Stage” we’re at as we go along.

Just about the first power mod that enthusiasts would like to do is to give their WRX or STI a voice with a replacement catback system. This is a good starting mod, as it doesn’t require any re-tuning and the install is as simple as undoing and redoing a few bolts. The catback replaces the stock piping you’ll find here in this old, yet still very helpful diagram:

It should be noted though that not all catbacks are created equal, and this rings true for all the other components of the exhaust system as well. Many people find it hard to justify spending $600-700 for a catback when they can buy one for $150-300 on eBay, but the truth really comes out in the manufacturing. All too often I hear accounts from eBay-brand exhaust owners who after only 1-2 years of ownership , must clean the rust off of their exhausts at regular intervals, even though they do not live in a climate where it snows and thus there’s no salt-based de-icing agents on the road. This really should not be the case whatsoever, and the higher priced exhausts are almost always more resistant to rust, so much that they maintain their quality for many years. Other differences to consider between the very inexpensive exhausts and the higher priced exhausts are the design of the exhaust itself, how well the exhaust fits on the car, how good the welds are on each of the pieces, and the manufacturer’s warranty. The difference is really in the detail.

The next thing to consider overall is the piping diameter and design, but honestly most people seem to read into this more than necessary. A turbo motor likes to breathe, and thus the better the exhaust flow, typically the better the car performs. Most catbacks and downpipes are made to be 3 inches in diameter for the most part, however many, if not most catbacks taper down to 2.5 inches at the end that bolts onto the downpipe. The reason for this is to make it easier for the exhaust to mate to the rest of the otherwise stock exhaust, but over the years some people have claimed that this tapering down is a huge and unacceptable hindrance. While this taper can be an issue with high horsepower levels (400+ whp) since it creates a bottleneck, the vast majority of WRX and STI owners, especially those who do not track, compete, or otherwise race their car on a regular basis (in other words, daily drivers) will never feel or notice this power difference. That isn’t to say that full 3-inch piping that does not taper down to 2.5 inches is a bad thing, rather it simply shouldn’t be of the utmost priority for the vast majority of Subaru owners out there. What really should be important though is whether or not the exhaust is straight-through or if it is baffled. Straight-through exhausts tend to be louder, but there are definitely some quiet ones out there. The problem with baffled exhausts is that while they tend to be more on the quiet side, the exhaust flow goes through a baffling chamber which causes the exhaust to be quiet. This interrupts the exhaust flow and thus will not make as much power as a straight-through exhaust. You’ll be able to tell the difference pretty easily: if you look down one end of the exhaust and can see light at the other end with little problem, you’ve most likely got a straight-through exhaust. Otherwise, the exhaust is most likely baffled, and the exhaust flow has to make some twists and turns in the baffling chamber before it exits out the other side.

Finally, probably the most important thing to consider about the catback of your choosing is how the exhaust itself sounds. Choosing an exhaust sound is much like choosing a set of wheels or a pair of shoes, since everyone has different tastes and needs. Some exhausts are deafening loud, whereas others are just as quiet as your stock exhaust. Generally speaking, the louder the exhaust, the more straight-through it is, and thus the more power it makes, but there will always be exceptions to this rule. If you live in a state where exhaust volume levels are strictly enforced, then you’ll definitely want to consider a good, straight-through, quiet exhaust. Otherwise, almost nothing sounds as good as a very loud WRX or STI, but just be prepared to deal with exhaust drone on the highway and having to yell simply to converse with your passengers.

That just about does it for part one. Be sure to do your research, watch some exhaust videos on your favorite video hosting website, ask your friends’ opinions, and be sure to contact us if you have any further unanswered questions. We’ve come across more exhausts than most other vendors in our day, so we’ll be happy to make a recommendation for your needs! Tomorrow, we’ll talk about the next component of the exhaust system: the downpipe.