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 aFe'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.
Testing In testing, the axle-back exhaust system resulted in gains up to +7 horsepower and +10 lbs. x ft. of torque verified by our in-house dyno
Aggressive Sound: Dual free-flowing mufflers are used to absorb high pitch tones producing a powerful sound and unleashing all available horsepower and torque.
Exhaust Valve: This axle-back exhaust system incorporates factory style NPP dual mode & AFM (active fuel management) exhaust valves which use the factory exhaust valve motors (not included). The valves helps regulate, direct and control the flow of exhaust gases by opening, closing, or partially obstructing passageways depending on throttle position for maximum performance.
Simple Installation: This MACH Force-Xp axle-back exhaust system uses factory mounting locations providing stability and a hassle-free installation.
Quad 4" Carbon Fiber Tips: Finishing off this system are quad light weight, 4” diameter, pure carbon fiber tips. The tips come with CNC-Machined laser-etched inserts, which give an aggressive yet elegant sporty look.
Leak-Free Seal: High quality band clamps are used for a complete 360 degree sealing surface.
Brushed 304 SS Construction: The performance axle-back exhaust system is constructed of 3" mandrel-bent, brushed 304 stainless steel tubing for maximum performance, corrosion resistance and strength eliminating cracking.
This System Fits: 2014-2019 Corvette (C7) Stingray 2017 Corvette (C7) Grand Sport
Note: Failures of original equipment AFM and NPP actuators are not covered by aFe POWER's warranty
All aFe exhaust systems are engineered and manufactured in our Corona, California facility.
Dyno-Proven Gains up to +7 HP & +10 Lbs. x Ft. TQ
Constructed from 100% Hand TIG-Welded, 3" to 2-1/2" Mandrel Bent, Brushed Finish 304 Stainless Steel Tubing
Includes Factory Style NPP Dual Mode & AFM Exhaust Valves
Utilizes Unique Dual High Flow, Stainless Steel Mufflers
Includes Quad 4" Diameter, Carbon Fiber Tips with CNC-Machined, Laser-Etched Inserts
Uses all Factory Hanger Locations for a Hassle-Free Installation