This 2.5" diameter performance Merge X-Pipe with Mid-Pipes creates power while adding a great sound. They will fit vehicles with and WITHOUT NPP. Borla(r) Cat-Back(tm) / Axle-Back systems used with this part do NOT include NPP valves. Borla(r) Performance Industries once again proves why we've led the aftermarket performance exhaust industry for over 40 years. Borla(r) has an exalted heritage with Chevrolet performance vehicles. From the C5R LeMans Winning Corvettes to privateers like KTEC Pratt-Miller Lingenfelter and Lou Gigliotti who have enhanced Borla(r)s knowledge of both the vehicle dynamics and power-plant engineering. The C6 is a muscle car with a big powerful engine and sophisticated sexy chassis. Borla(r) has always used the transfer of technology from racing to the street as a tool and the C6 plays right into that wheelhouse. With an experienced R&D staff the Borla(r) team gave the C6 the attention it deserves. Airflow management and exhaust engineering is a science with which Borla(r) has more experience than anyone in the exhaust aftermarket. Borla(r) Performance Industries the original pioneers of premium high quality T-304 austenitic stainless steel (superior to 409 or aluminized steel) free-flow exhaust utilizes patented award and race winning technology to deliver quality sound performance gains and enhanced fuel economy all with an easy bolt-on installation. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. All Borla(r) street products carry an unsurpassed written million-mile warranty.