Borla Cat-back TM & Rear 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 BORLAÂ® Sound of Power respected by motoring enthusiasts everywhere.Each system is built from premium 300-series 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 youâ€™d expect from the worldâ€™s most experienced (and most winning) exhaust brand.