Borla's "Aggressive" catback exhaust for the WRX & STi features 2.5" diameter piping, no resonators, and a straight through muffler for improved performance and sound for mildly modified & stock cars. This exhaust is designed to mate perfectly to a stock downpipe, and, unlike the Hush and XR-1, cannot be upgraded with the 3" adapter so keep this in mind; if you're planning on changing out the stock downpipe for a full 3" piece, it will be difficult to mate this exhaust to it. This system is designed for the end-user that wants some more sound and power but isn't planning on heavily modifying their WRX or STi. This system is stainless steel and backed by Borla's million-mile warranty.

BORLA Cat-Back™ exhausts feature patented, straight-through and multi-core technology to unleash hidden horsepower. Increased exhaust velocity adds power, driving excitement, fuel economy and the distinctive BORLA Sound of Power respected by motoring enthusiasts everywhere. Each system is built from premium austenitic stainless steel, superior to T-400 series knockoffs, to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow and power, and precision computer-controlled CNC manufacturing ensures an accurate fit. Best of all, BORLA stands behind every system with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.