This 2.5" diameter into dual 2.25" BORLAÂ Cat-Backâ„¢ system was specifically designed to enhance the power and sound of the Frontier equipped with 3.8L engine. The system features the classic S-Type sound that gives you a powerful performance sound with no drone. It features 2 full Tail Pipes (Not a single tail pipe with dual tips) with single 4" round black chrome on T-304 stainless steel tips on each tail pipe and a dual side exit configuration. Using BORLAÂ 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. A system is also available with bright chrome on T-304 stainless steel tips. 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. 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. The entire system is made of T-304 stainless steel and utilizes computer numerical control (CNC) manufacturing techniques that ensure an accurate fit. All this is backed by our unsurpassed Million Mile Warranty.