NPP exhaust
Thread Starter
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
NPP exhaust
Hey guys, quick question about the NPP exhaust system. I just purchased a 2007 base coupe with 10k miles. I would like to find an install a set of NPP exhaust on the car. I had them on my 2012 grand sport and fell in love with them. Anyway, my question is what year NPP exhaust will fit on the 2007 base coupe? Thanks for any help
Pro
Joined: Dec 2007
Posts: 595
Likes: 241
From: Maine
2022 C6 of the Year Finalist - Unmodified
You can put on any year if you change the h-pipe/x-pipe. If you don't want to do that you need NPP mufflers from a 2008 only.
That is unless you have welding skills or take it to an exhaust shop for them to fit up.
That is unless you have welding skills or take it to an exhaust shop for them to fit up.
Safety Car
Joined: Aug 2017
Posts: 4,931
Likes: 2,340
From: Etobicoke (Toronto) Ontario
Any of the NPP-option C6 mufflers can be attached to your existing exhaust system by a competent muffler shop. (keyword being 'competent'). They'll just cut off the existing cans and weld on the NPP-option cans. However, it's not going to behave like a car that was optioned with NPP from the factory - you won't get automatic opening of the butterflies with throttle and rpm. There is a product called 'NPP in a box' that has the hardware and instruction to allow you to connect a vacuum line and solenoid and operate the butterflies with a remote. Other folks on the forum have built their own control system for relatively little $$ using off the self tubing, some wiring, a mechanical switch, and a vacuum solenoid. You can even buy a remote system for relatively little $$ and use it to control a vacuum solenoid, like this one:
This looks a lot like the one supplied in the Mild2Wild product, only a lot less $$. I think all you'd need to do is connect a fused wire to the control box to power it.
Apparently, you can even hook up the vacuum tubing directly to the vacuum pots on the mufflers and depend on a drop in vacuum during acceleration to open the butterflies.
This looks a lot like the one supplied in the Mild2Wild product, only a lot less $$. I think all you'd need to do is connect a fused wire to the control box to power it.
Apparently, you can even hook up the vacuum tubing directly to the vacuum pots on the mufflers and depend on a drop in vacuum during acceleration to open the butterflies.
Safety Car
Joined: Jun 2001
Posts: 4,397
Likes: 336
From: Haymarket VA
after buying some used bi-mode mufflers and having them installed I bought and installed my own NPP in a box using the below:
vacuum controller
dead pedal switch
add a circuit fuse tap
vacuum tubing - 5/32 - its a tough fit but will go on the back of the intake port like factory
I routed the tubing down the side like many have suggested before.
vacuum controller
dead pedal switch
add a circuit fuse tap
vacuum tubing - 5/32 - its a tough fit but will go on the back of the intake port like factory
I routed the tubing down the side like many have suggested before.
Melting Slicks
Joined: Jul 2011
Posts: 2,800
Likes: 166
2023 C6 of the Year Finalist - Modified
Idk where people are getting their information but the simplest way of doing this besides buying the npp vacuum lines is to purchase an npp axleback off a 2008 base model c6. Later years have different clearances and fitment. That's why you see c6 aftermarket exhausts broken out between 2005-2008 and 2009-2013.
If you have metal fabrication skills yes you can hack off the mufflers off any npp year and just weld the mufflers to your existing over axle pipes.
I might still have a set of just npp mufflers from a 2008 if you're interested.
If you have metal fabrication skills yes you can hack off the mufflers off any npp year and just weld the mufflers to your existing over axle pipes.
I might still have a set of just npp mufflers from a 2008 if you're interested.
Thread Starter
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
OK guys as I said this car is brand new to me. It is much different than my previous 2012 grand sport. The grand sport exhaust NNP could seen clearly from looking directly behind the car. So the point of this is talk about me being f***ing stupid, I crawled under the car yesterday and actually this car is equipped with NPP Exhaust system. The valves are tucked up high behind the rear valance. You talk about feeling like an idiot! Anyway they are not functioning correctly whatsoever as the valves are always open. I’m going to have to trace down and see what the previous owner did or didn’t do and try to locate whatever controller is in the vehicle. Thanks for your input but boy do I feel like a jackass.
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Melting Slicks
Joined: Jul 2011
Posts: 2,800
Likes: 166
2023 C6 of the Year Finalist - Modified
OK guys as I said this car is brand new to me. It is much different than my previous 2012 grand sport. The grand sport exhaust NNP could seen clearly from looking directly behind the car. So the point of this is talk about me being f***ing stupid, I crawled under the car yesterday and actually this car is equipped with NPP Exhaust system. The valves are tucked up high behind the rear valance. You talk about feeling like an idiot! Anyway they are not functioning correctly whatsoever as the valves are always open. I’m going to have to trace down and see what the previous owner did or didn’t do and try to locate whatever controller is in the vehicle. Thanks for your input but boy do I feel like a jackass.
Thread Starter
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
I just checked and the fuse IS there for the NPP exhaust. However, I did find a Mild to Wild wired into the fuse panel but not plumbed where it should be on the lower right…its in the same lines of vertical fuses just plumbed into the very top fuse. Rather than disturb it maybe I should locate the vacuum solenoid to see if it functions. Am I correct in saying that the solenoid is located behind the inboard passenger side tail light?
Safety Car
Joined: Aug 2017
Posts: 4,931
Likes: 2,340
From: Etobicoke (Toronto) Ontario
There are 2 ways to hook up the controller. See the attached file. You do need a remote fob to operate the switch, so if you don't have either of the 2 that came with the unit, then unfortunately you are SOL. The unit remembers its last setting so if it was left in the open position that's the way it remains without the fob. Once you see how it's supposed to be installed then you can unplug it and see if a fuse works.
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
A 2007 Vette won't have an "NPP fuse" as 2005 - 2007 Vettes had no NPP option. A "mild to wild" switch won't work as you don't have the controller bits that come with factory equipped NPP optioned Vettes. With no controller and/or no vacuum going to the mufflers, they will stay open all of the time. The LS2 didn't have the vacuum hose barb on the back of the intake manifold as no LS2 powered Vettes were available with the NPP option. If you do have "NPP in a box, you'll see the vacuum controller in the right rear cubby. You'll also see vacuum lines connected to the vacuum pots on the mufflers.
You need to figure out what you have before proceeding any further. I'm running mine off of direct manifold vacuum with no controller. At cruise it's stock quiet. Press hard on the right hand pedal and the flaps open instantly. No need to push a button first. I initially installed a used NPP in a box kit that didn't work. I bypassed the controller to run straight vacuum and liked it better. I never saw the need to run around with the flaps open. Just too damn loud with cam, headers, and no cats.
You need to figure out what you have before proceeding any further. I'm running mine off of direct manifold vacuum with no controller. At cruise it's stock quiet. Press hard on the right hand pedal and the flaps open instantly. No need to push a button first. I initially installed a used NPP in a box kit that didn't work. I bypassed the controller to run straight vacuum and liked it better. I never saw the need to run around with the flaps open. Just too damn loud with cam, headers, and no cats.
Pro
Joined: Dec 2007
Posts: 595
Likes: 241
From: Maine
2022 C6 of the Year Finalist - Unmodified
The LS2 does have the barb on the back of the intake mani, it's just capped off from the factory. I just installed NPP mufflers on my 2007 and uncapped that barb to use for them.
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
I’m doing the straight vacuum line on mine too, but I also bought the bmw solenoid (ebay $18) that is identical to the GM one that will allow on/off with a 12volt source and a switch
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
Learned something new today. I don't remember that hose barb being there....but, that was a long time ago that I fooled with an LS2 intake manifold. Or maybe some had it and some didn't? All of the LS3 intake mani's that I've seen had it and I think that's where the factory NPP system gets it's vacuum. I've never seen any other line connected there. Makes me wonder why GM put the hose barb there with there being no NPP option on LS2 powered Vettes.
Thread Starter
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Got to the bottom of all this and got them working. Thanks for all the good info guys. This car has been lowered quite a bit so it has been impossible to get underneath it till today……even under the exhaust. Once up in the air, Discovered the car has a Billy Boat Fusion exhaust system. Found the vacuum line leading from the intake manifold was disconnected from the rear mounted "vacuum accumulator " which was fed electrically by the controller mounted in the inside fuse panel. Hope that makes sense. The bottom line is the the mufflers are now seeing manifold vacuum through the accumulator. Thanks for all the suggestions and help.
