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„¢ delivers the Aggresive ATAK sound. ATAK Acoustically-Tuned Applied Kinetics technology is based on specifically-tuned attributes of the internal muffler cores which are calibrated on a vehicle-by-vehicle basis to deliver the most desirable sound. Even though the sound on the exterior is uncompromising the sound in the cabin is devoid of harsh resonance a product of painstaking engineering and over 40 years of experience. The system features dual 4" round polished T-304 stainless steel tips on each muffler. 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 youâ€d expect from the worldâ€s most experienced (and most winning) exhaust brand.