For the 2002-2007 Subaru WRX and STI owners looking to keep their stock muffler, or use a different axle-back, the Turbo XS Stealthback is the exhaust for you. This system for the WRX/STI includes Turbo XS's 4" bellmouth downpipe, which tapers to 3" into a 3" high-flow cat (or racepipe in the catless version), and then into a 3" midpipe. Turbo XS's cat to downpipe connection features an OEM style ball-and-socket design with a donut gasket, to allow exhaust movement while maintaining a tight seal.
In addition, the Turbo XS midpipe is full 3" diameter, but has a unique rear flange that will either allow you to install a stock-type 2.5" diameter muffler, or a full 3" rear muffler like the Turbo XS. The Turbo XS WRX & STi Stealthback exhaust is also available in a catless version, which includes a Turbo XS catless racepipe instead of a high-flow catalytic converter.
Subaru STI 2004-2007
Subaru WRX 2002-2007
These parts are the latest version of the 02-07 design (part number WS02-) and are NOT compatible with the older style TurboXS exhaust parts (part number WS-).