Dual Mode Exhaust (NPP)
Thread Starter
4th Gear
Joined: Oct 2013
Posts: 4
Likes: 0
Dual Mode Exhaust (NPP)
Just bought a 2011 base with dual mode exhaust. I see NPP as an option code on the build sheet but no reference in the owners manual. Car has a little chintzy looking remote with "off" and "on" buttons that seem to control it. Am I correct in assuming this exhaust is not factory controlled other than automatically and that there has been a modification done that controls this feature ith the aforementioned remote? I assume this has been discussed and re-hashed on here a million times, forgive me...I'm a newbie here.
Burning Brakes
Joined: Jun 2013
Posts: 867
Likes: 26
From: SW Ohio
The NPP option is a set of solenoid-controlled/vacuum-operated valves in the mufflers that reroute the exhaust gases directly thru the open pipe vs thru the packing in the cans. Louder with less restriction and another 6 HP at peak when the valves are open. From the factory, the valves are normally closed at idle and up to about 3400 RPM, at which point the ECM sends a signal to a solenoid to open the vacuum lines which then pull the exhaust valves open. I presume the remote is from one of the aftermarket companies--Sunset Orange Creations is one--that gives you manual control of the valves. If it's one of the newer units, it can be installed to either be in the open or closed mode on start-up.
Last edited by icntdrv55; Nov 30, 2013 at 10:46 AM.
