The first step in adding power to your Subaru WRX is allowing your motor and turbocharger breath more freely. By adding a larger diameter performance exhaust it allows the exhaust gases to flow freely, reduces back pressure and removes or replaces the stock catalytic converter. An aftermarket exhaust is also much lighter then your stock exhaust system.
There are three different type of performance exhaust systems to choose from:
1. Turbo back exhaust (TBE): This exhaust system a complete exhaust starting from the outlet of the turbo all the way back to the exhaust tip. This system delivers the most power out of the three, and can make upwards of 15-30hp. Please note that if you run a Turboback exhaust system on your WRX or STi you will need to have some kind of engine mangment like a Cobb Tuning Access port or something similar.These exhaust systems are generally the loudest out of the three due to removal of factory restriction, catalytic converter, and larger diameter exhaust piping.
2. Cat back exhaust (CBE): This Exhaust system starts right after your catalytic converter,to the exhaust tip. Adding a catback exhaust system will improve performance, add horsepower, and gain torque. Adding a catback exhaust can make upwards of 5-15HP, and allows you to add a performance downpipe,and midpipe of your choice. With this WRX exhaust system you have better control of finding the exhaust that fits your sound, and performance needs. Another benefit is that a catback exhaust system will not trigger a Check engine light (CEL) to come on, and you will not need your tune the ECU.
3. Axle back exhaust (ABE): This exhaust only consist of your muffler canister. A axleback exhaust system is good if you want to gain a few extra horsepower while still maintaining stock like sound. this system will also not cause a Check engine light (CEL) to come on, and can make upwards of 5-10HP.
PLEASE NOTE: Some aftermarket catback exhausts feature a stock-type flange for easy bolt-on installation to a stock downpipe Borla, Blitz, GReddy, etc. Other offer a 3" flange like Perrin, HKS, Invidia, etc. for optimal flow when used with a 3" downpipe. This should be considered when upgrading your WRX or STi's exhaust.
Exhaust Piping Size: Performance exhaust system come in three different diameters. below you can choose the size that suites your needs. Choosing a larger exhaust than needed for your level of modification has no disadvantages other than cost, and possible less ground clearance issues.
- 2.5" diameter is good for 300-350HP
- 3.0" diameter is good for 400-600 HP
- 3.5" diameter is good for 600HP +
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