This 2.5" diameter Merge X-Pipe will fit vehicles with and WITHOUT NPP. Borla(r) Cat-Back(tm) / Axle-Back systems used with this X-Pipe do NOT include NPP valves. This performance X-Pipe creates power while adding a great sound to the C6 Corvette systems. In testing customers and racers alike noticed the power increase you've come to expect from Borla(r) and all commented on the great exhaust tone being emitted. This sophisticated component (Part #60505) is a perfect compliment to the famous Borla(r) Cat-Back(tm) / Axle-Back systems and is even lighter than the stock system mainly due to the premium high-quality T-304 lightweight stainless steel used in every Borla(r) exhaust component. Additional attributes include an extremely simple bolt-in replacement for the factory mid-pipe that further enhances that famous Borla(r) growl of power. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. While many exhaust companies talk about racing Borla(r) exhaust components are tested every single weekend on race tracks around the world. The Borla(r) success is unmatched and that effort transfers to the Borla(r) street systems. Borla(r) backs this part with an unequaled Million-Mile warranty.