This system will fit vehicles with and without NPP valves. BORLA system does NOT include NPP valves. The single 2.5" diameter Into the muffler with dual 2" out Cat-Backâ„¢ system delivers the S-Type II sound which utilizes a muffler design that eliminates sound frequencies that are often associated with resonance or drone. The exhaust exits thru dual 4" round polished T-304 stainless steel tips on each muffler. BORLA 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 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 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 youâ€d expect from the worldâ€s most experienced (and most winning) exhaust brand.