THIS SYSTEM WILL ELIMINATE THE FACTORY NPP & AFM VALVES
Pipe Diameter:2.75" into muffler, dual 2" out
The Nuclear Propulsion Package (NPP) option is a vacuum controlled valve on the factory exhaust which is controlled by the ECU. It will open and close based on RPM and throttle position. The NPP feature offers a more aggressive exhaust note when driving in sport/track mode, or at higher RPM's as listed below.
The valves will be open for the first two seconds that the car is started. It requires time for the vacuum pressure to build to close the valves. After that The operation of the NPP is normally closed, open on demand. Have someone stand behind the car and bring up the RPM to 3,500 and you should see the valves open. The butterfly operation is tied to the throttle position sensor and the RPM. It uses the throttle position to determine driver intent. Under normal operation the valves work as follows:
Below 30% throttle and 3,500 rpm the valves are closed. Above 30% throttle and 3,500 rpm the valves will open. Between 30% throttle and 80% throttle and above 3,500 rpm the valves are open.
Above 80% throttle and above 2,800 rpm the valves are open.
GM Active Fuel Management (AFM) valves deactivate (4) of the (8) cylinders in a V8 engine when operating in lower RPM's (typically under 4K). Test results have indicated that retaining this feature can improve fuel economy by up to 7.5%. Some of Borla's options retain this feature with their valves while others eliminate them entirely along with the factory NPP valve feature (mentioned above). Carefully review the notes we provide to determine if you are ordering the correct system.
This Axle-Back system is NOT equipped with AFM or NPP valves. System features polished T-304 stainless steel tips. Optional system are available. BORLA® Cat-Back™ & Axle-Back exhaust systems feature patented straight-through and multi-core technology designed to unleash hidden horsepower. Increased exhaust velocity adds Optional system are listed below. BORLA® Cat-Back™ & 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-controlled CNC manufacturing ensures an accurate fit.
*** BORLA®'s C7 Corvette Axle-Back 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***