This 2.75" diameter into dual 2" BORLAÂ Cat-Backâ„¢ system has been tuned for flow performance and sound specifically for the 2.5L 4 cylinder engine in the K5 GT. The system delivers the sporty S-Type sound without any drone in the cabin. The exhaust exits thru dual 3.5" round black chrome on T-304 stainless steel tips on each muffler assembly. Using BORLAÂ Stainless Steel Polish PN# 21461 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. BORLAÂ Cat-Backâ„¢ & 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. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. Each BORLAÂ Exhaust System is built from premium T-304 series stainless steel to give you the absolute best in performance and durability. We strive to provide you with the highest quality products and stand behind our systems with a Million-Mile Warranty.