This 2.5" diameter True Dual BORLA® Cat-Back™ system was designed specifically for the Q50. It features a Merge X-Pipe and Borla's patented Polyphonic Harmonizer technology for increased performance and improved sound with no drone inside the vehicle. BORLA®'S Polyphonic Harmonizer Technology 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. Completely eliminating the turbulent center intersection of a standard X-Pipe, The classic S-Type sound level delivers a sporty sound and a deeper tone without any drone inside the cabin. The system has a single 4.5" black chrome on T-304 stainless steel tip on each tail pipe. Using BORLA® Stainless Steel Polish p# 21461 is NOT recommended with these black chrome tips. We suggest cleaning the tips with hot water and a microfiber cloth. Systems with bright chrome on T-304 stainless steel tips, and carbon fiber tips are also available. 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, high-quality 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 a 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.