Fits both S4 with Sport Diff or without. System contains a merge X-Pipe for increased performance and improved sound. Features polished T-304 stainless steel tips. BORLA® Cat-Back™ & Axle-Back exhaust systems 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 T-304 austenitic 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-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.