This Borla(r) Cat-Back(tm) system is designed specifically for the 2.4L engine in the WRX. The 3" diameter single exit Cat-Back(tm) system features Polyphonic Harmonizer technology which utilizes patented units that contain pipes of different diameters and lengths to create multiple exhaust notes that harmonize to deliver a clean rich full-bodied sound and the aggressive ATAK(r) sound with no drone in the cabin. The system exits in the rear on the passenger side and features laser welded muffler end caps for a clean appearance. Extended Polyphonic Harmonizer muffler core design exits inside the 4.5" brushed T-304 stainless steel tip for a custom look. The tip has a laser cut Borla(r) logo. Borla(r) Cat-Back(tm) and Axle-Back exhaust systems feature patented straight-through and multi-core technology designed to unleash hidden horsepower. Increased exhaust velocity adds power driving excitement fuel economy and the distinctive Borla(r) Sound of Power respected by motoring enthusiasts everywhere. Each system is built from premium T-304 stainless steel superior to T-400 series knockoffs (such as 409) to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. Best of all Borla(r) 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.