The addition of a performance uppipe is a favorite modification among die-hard Subaru tuners around the globe. Invidia's Subaru WRX uppipe is a catless direct bolt on replacement for the factory uppipe in your 02-07 WRX or STI. Removing your WRX's restrictive factory uppipe increases exhaust flow to the turbocharger and in return improves turbo spool, throttle response and power output by approx 7-10hp. The Invidia WRX/STI uppipe has a bung for your stock EGT sensor, but can easily be plugged when used with later models that do not have an EGT in the uppipe (plug not included). The Invidia uppipe even includes replacement studs for added installation convenience. 02-05 WRX models have a pre-turbo catalyst, making this uppipe a major performance improvement. Though the 06-07 WRX and 04-07 STI do not have a cat in the factory uppipe, this product will still improve throttle response and drivability.