This 3.5" diameter into dual 2.25" Cat-Back™ system delivers the aggressive ATAK® sound with no drone inside the vehicle. The system features single 4" round black chrome on T-304 stainless steel tips on each tail pipe. Using BORLA® Stainless Steel Polish p# 21499 is NOT recommended with these black chrome tips. We suggest cleaning the tips with hot water and a microfiber cloth. A system with bright chrome on T-304 stainless steel tips is also available. BORLA® Cat-Back™ 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® 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® 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.