This Axle-Back system is equipped with NPP valves. Optional system are available. 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-controlled CNC manufacturing ensures an accurate fit. Borla's C7 Corvette rear section exhaust systems are covered under our Million-Mile Warranty for non-moving parts, the exhaust valves are warrantied for 3 years. Failures of original equipment AFM and NPP actuators are not covered by the Borla warranty.