2007 Base exhaust valve help.
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Intermediate
Joined: Apr 2025
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2007 Base exhaust valve help.
Base coupe 1LT no frills. I’d like to wake this baby up and keep finding more questions than answers on my particular year when searching. It looks like factory NPP exhaust as it has valves and fuse in the lower right slot (which I’ve pulled and no changes) in hopes of opening valves. I’d like to go “mild to wild” with switch or remote sooner than later and eventually go long tubes/catless x and maybe keep factory axle-back. New to the C6 world here so any help appreciated. I don’t have the window sticker to show options but I assume if it has valves and fuse it should be NPP and/or defeat-able(?). Thanks!
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Welcome to the Forum, hope you find info you need. Moving you here for further discussion. Good Luck
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Pro
Joined: Oct 2024
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From: WI
You can email your local Chevy dealer with your VIN and request an RPO list and they will provide it.... but I think it's clear that you have the NPP option as evidenced by the valves on the mufflers. If your system is not activating at higher RPMs then you likely have an electrical issue or vacuum issue. Start with a good visual inspection of all wires and vacuum lines first to see if there are any obvious broken connections.
Thread Starter
Intermediate
Joined: Apr 2025
Posts: 37
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You can email your local Chevy dealer with your VIN and request an RPO list and they will provide it.... but I think it's clear that you have the NPP option as evidenced by the valves on the mufflers. If your system is not activating at higher RPMs then you likely have an electrical issue or vacuum issue. Start with a good visual inspection of all wires and vacuum lines first to see if there are any obvious broken connections.
Thanks for that. I’ll get with our Chevy dealer for the list I can hear the valves open if I punch it and fairly certain they’re functioning. I’ll warm it up and rev above 3500 with my phone recording to be sure. Just perplexed why pulling the fuse has no effect.
Le Mans Master
Joined: Dec 2005
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From: Southeast TX
Bi mode exhaust (NPP option code) wasn't an option in 2007. It started in 2008. 2008 mufflers from an NPP optioned code Vette will bolt on with no issues. 2009 and up NPP option code mufflers aren't a bolt on with no issues for your 2007.
If you're adding headers, just order the mid pipes for the bi mode mufflers you find. Any of them can be made to fit with the proper mids. NPP, Z06, or ZR1. You can spend as much or as little as you want to control the valves in the mufflers.
On mine, I run a manifold vacuum line back to the mufflers with no controller. It's in the quiet mode unless I step hard on the go pedal....then they get loud. I have no desire to run around in the loud mode. If you do, then you need something like the NPP in a Box controller where you can choose loud or quiet at any time.
If you're adding headers, just order the mid pipes for the bi mode mufflers you find. Any of them can be made to fit with the proper mids. NPP, Z06, or ZR1. You can spend as much or as little as you want to control the valves in the mufflers.
On mine, I run a manifold vacuum line back to the mufflers with no controller. It's in the quiet mode unless I step hard on the go pedal....then they get loud. I have no desire to run around in the loud mode. If you do, then you need something like the NPP in a Box controller where you can choose loud or quiet at any time.
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Thread Starter
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Bi mode exhaust (NPP option code) wasn't an option in 2007. It started in 2008. 2008 mufflers from an NPP optioned code Vette will bolt on with no issues. 2009 and up NPP option code mufflers aren't a bolt on with no issues for your 2007.
If you're adding headers, just order the mid pipes for the bi mode mufflers you find. Any of them can be made to fit with the proper mids. NPP, Z06, or ZR1. You can spend as much or as little as you want to control the valves in the mufflers.
On mine, I run a manifold vacuum line back to the mufflers with no controller. It's in the quiet mode unless I step hard on the go pedal....then they get loud. I have no desire to run around in the loud mode. If you do, then you need something like the NPP in a Box controller where you can choose loud or quiet at any time.
If you're adding headers, just order the mid pipes for the bi mode mufflers you find. Any of them can be made to fit with the proper mids. NPP, Z06, or ZR1. You can spend as much or as little as you want to control the valves in the mufflers.
On mine, I run a manifold vacuum line back to the mufflers with no controller. It's in the quiet mode unless I step hard on the go pedal....then they get loud. I have no desire to run around in the loud mode. If you do, then you need something like the NPP in a Box controller where you can choose loud or quiet at any time.
Thanks for the good info. I had the RPO sheet sent to me and you are correct, no NPP listed. I’m guessing then there’s no easy way to manually open the valves on the 07 (?) and muffler swap is only option. I actually like the scream it emits when goosed hard as it is now. I just want to give it some rumble at idle and slow speeds. Sounds kinda wimpy compared to it’s looks.
Burning Brakes
Joined: Jun 2005
Posts: 914
Likes: 129
From: Toronto
Previuos owner installed the factorry NNP mufflers on your 07. I have an 07 and removed the factory mufflers and installed the NPP mufflers years ago with the mild to wild controller (NPP in a box kit with wireless remote). I also installed the foot switch in the dead pedal about a year later its way easier than fumbling with the wireless remote. I can either use the wireless remote or the foot switch both work but have been using the foot remote all the time. Best of both worlds-quiet when ever you want and loud when ever you want...
Last edited by crusher1; May 22, 2025 at 10:18 PM.
Thread Starter
Intermediate
Joined: Apr 2025
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Previuos owner installed the factorry NNP mufflers on your 07. I have an 07 and removed the factory mufflers and installed the NPP mufflers years ago with the mild to wild controller (NPP in a box kit with wireless remote). I also installed the foot switch in the dead pedal about a year later its way easier than fumbling with the wireless remote. I can either use the wireless remote or the foot switch both work but have been using the foot remote all the time. Best of both worlds-quiet when ever you want and loud when ever you want...
Burning Brakes
Joined: Jun 2005
Posts: 914
Likes: 129
From: Toronto
Doesnt matter fuse or no fuse--wont work. valves are programmed to open up above 3000 rpm on 08 and up factory installed NPP. You need the NPP in a box kit like I mentioned before with the vacuum lines to control the open and closing of the valves on the mufflers.
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Burning Brakes
Joined: Jun 2005
Posts: 914
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From: Toronto
You sure you dont have the NPP in a box kit already in the car when you bought it? And it was left in the quiet mode? your just missing the wireless remote? never given to you when you bought the car. Which ever owner installed the mufflers they must have installled the NPP in a box kit otherwise whats the point of just putting the mufflers on without anyway to control the flaps--open or closed. See if you have the vacuum lines installed on the actuators that open and close the flaps on the mufflers see pic below for reference. You will have to crawl under the car and take a quick look. There should be vacuum lines connected to the nipples on the actuators on each muffler
Race Director
Joined: Mar 2008
Posts: 12,413
Likes: 502
From: Rio Rancho NM
Even with the valves open its still quiet. What a name though huh? Genius marketing because there is nothing "wild" about NPP mufflers on a stock vette when open but it sells. I put headers on my car with no cats. Now it's pretty wild when I go full throttle. You will want headers after you hear how lame the "wild" is on a stock car.
Team Owner
Joined: Mar 2002
Posts: 44,671
Likes: 1,830
From: Huntsville AL
I have NPP on my 2012 GS and to be honest can't tell the difference in sound at 3000 RPM or above. 
