Borla's XR-1 WRX & STI catback exhaust features 3" piping with Borla's patented XR-1 multi-core muffer for optimal flow. This system does not use a resonator like the Hush, so it has a deep, powerful tone. The section of the catback that bolts to the downpipe is slip-fit, and can be replaced with the 3" adapter for future upgradability.

The downpipe section Borla includes will bolt perfectly to your stock downpipe, but the optional 3" adapter simply bolts on and removes the bottle neck if you plan to use a 3" downpipe. Backed by Borla's million mile warranty, and constructed of stainless steel -- this is a great performing catback for your WRX or STI.