NPP Exhaust system
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
NPP Exhaust system
I'm looking to purchase an NPP exhaust system to install on my 2005 C6 Base. I'm having a little trouble determining what I need to make my Vette sound a little better without being obnoxious. I spoke with a local muffler shop that does a lot of Corvette work, and he initially recommended a Flowmaster Axle back system, at a cost of $2,100, but then said my best bet would be to find a used NPP system, but to make sure it comes from an automatic vehicle, because the automatic differs from the manual system.
My questions are:
Which vehicles have the NPP system that is compatible to be installed on my '05 Base?
Is there a difference in the two systems (automatic vs. manual)?
Thanks for your help!
My questions are:
Which vehicles have the NPP system that is compatible to be installed on my '05 Base?
Is there a difference in the two systems (automatic vs. manual)?
Thanks for your help!
Racer
Joined: Sep 2018
Posts: 314
Likes: 81
From: Virginia
I just did a NPP add to a 2005 M6. It was part of heads, cam, headers, etc. build.
Before the NPP add, I did the old school muffler mod. Sound much better for about $15 in parts.
Some slight drone between 1600 to 1850 or so. My car is a manual so RPM was easy to control.
See post #175
https://www.corvetteforum.com/forums...ler-mod-9.html
Before the NPP add, I did the old school muffler mod. Sound much better for about $15 in parts.
Some slight drone between 1600 to 1850 or so. My car is a manual so RPM was easy to control.
See post #175
https://www.corvetteforum.com/forums...ler-mod-9.html
Team Owner
Joined: Nov 2006
Posts: 21,136
Likes: 212
From: Long Island New York
Some years back I bought a used NPP exhaust for my 06 auto I don’t recall needing to get one specifically for an automatic. I’m pretty sure it doesn’t matter but check me on that.
While you’re at it get an NPP in a box kit to allow you to open/ close the flaps anytime you choose. As a bonus for us 05-06 cars it’s easily programmed into one of your visor garage door buttons.
While you’re at it get an NPP in a box kit to allow you to open/ close the flaps anytime you choose. As a bonus for us 05-06 cars it’s easily programmed into one of your visor garage door buttons.
Safety Car
Joined: Aug 2017
Posts: 4,243
Likes: 1,133
From: North Myrtle Beach SC
You need NPP mufflers from a 2008 LS3 corvette.
not sure but I think you can also use mufflers from 2009-2013 IF you use the 2009-2013 midpipe too
not sure but I think you can also use mufflers from 2009-2013 IF you use the 2009-2013 midpipe too
Last edited by farmington; May 27, 2020 at 04:45 PM.
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
I have located some NPP mufflers from an '08. How badly do I need the either the NPP in a Box, or Mild 2 Wild. Will this be obnoxiously loud with them open?
Instructor
Joined: Apr 2014
Posts: 146
Likes: 11
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Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
I have my ZR1 mufflers hooked up to manifold vacuum with no controller. If I stomp it, vacuum goes to 0 and the flaps open immediately. Just cruising around, they stay closed. I have a heads, cam rig with long tubes and no cats. It actually sounds good, to my ear anyway, even with the flaps closed. At WOT, with the flaps open, it screams like a banshee. I have a controller sitting in my garage. Don't know that I'll ever install it. Pretty happy with it as is.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,108
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
All you "need" is just the mufflers (no pipes) and a method to control the valves/flaps. Forget the pipes or what year or model they came from, unless you have a preference for the slight tone difference. Simply cut the pipe off your current mufflers and weld it to the bi-mode mufflers, which assures you won't have an interference problem. Assuming you buy from a non-local source, the lower cost of shipping after cutting the pipes from the mufflers will easily compensate for the cost of welding them to your current pipes.
Since the valves/flaps are normally open (loud), they require a vacuum source to close (quiet) them. The absolute quickest/cheapest way is to run a hose from an engine source through the driver area to the mufflers and pinch the hose shut with a snap clamp to go loud. All the other options do basically the same thing, but with electric controls that may even be operated remotely. Maybe old motorhead ^ would sell you his never-used controller?
Since the valves/flaps are normally open (loud), they require a vacuum source to close (quiet) them. The absolute quickest/cheapest way is to run a hose from an engine source through the driver area to the mufflers and pinch the hose shut with a snap clamp to go loud. All the other options do basically the same thing, but with electric controls that may even be operated remotely. Maybe old motorhead ^ would sell you his never-used controller?
Pro
Joined: Sep 2015
Posts: 537
Likes: 191
From: Pennsylvania
I added the NPP mufflers from an 08 on to my 07. No modifications were needed. It was a direct hookup. I then put the Mild 2 Wild setup on so I could control the noise. I like the quiet when cruising.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Yeah, I'd be willing to do that. It's been running on manifold vacuum without any controller for over a year now. Don't think I'll ever use that controller. Also have a set of Z06 cans without the over the axle pipes. The tips are buggered up on the bottom side. Can't see it unless you're under the car. Hell, the first thing I did when I received my really nice ZR1 mufflers is etch the chrome tips, add a coat of high temp primer, and a coat of high temp flat black. Looks good and I never have to clean and polish them. I like to drive my Vette, not rub on it. Don't want to fool with shipping on the mufflers. I'm located west of Houston. $100 takes them. I want 85% of new price for the controller. PM if interested.
Advanced
Joined: Mar 2012
Posts: 94
Likes: 37
From: Liberty Twp OH
Is the controller you are referring to the one behind the rear taillight?
Any chance you could post a photo?
My NPP stopped working and I assume that my controller has burned out.
Any idea how to best confirm the problem is the controller?
Any chance you could post a photo?
My NPP stopped working and I assume that my controller has burned out.
Any idea how to best confirm the problem is the controller?
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
Yeah, I'd be willing to do that. It's been running on manifold vacuum without any controller for over a year now. Don't think I'll ever use that controller. Also have a set of Z06 cans without the over the axle pipes. The tips are buggered up on the bottom side. Can't see it unless you're under the car. Hell, the first thing I did when I received my really nice ZR1 mufflers is etch the chrome tips, add a coat of high temp primer, and a coat of high temp flat black. Looks good and I never have to clean and polish them. I like to drive my Vette, not rub on it. Don't want to fool with shipping on the mufflers. I'm located west of Houston. $100 takes them. I want 85% of new price for the controller. PM if interested.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
This is what I have. It's made to control the bi mode mufflers on a Vette that didn't come with a bi mode exhaust. https://www.corvettemods.com/C6-Corv...yABEgLO1vD_BwE
I would take $170 + the ride for the NPP in a box.
I would take $170 + the ride for the NPP in a box.
Last edited by old motorhead; May 29, 2020 at 06:06 PM.
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
This is what I have. It's made to control the bi mode mufflers on a Vette that didn't come with a bi mode exhaust. https://www.corvettemods.com/C6-Corv...yABEgLO1vD_BwE
I would take $170 + the ride for the NPP in a box.
I would take $170 + the ride for the NPP in a box.
I think I'm going to wait to see how loud this is before I go after it.
Thanks again for your help! This forum is an awesome place for answers and to just hang out. I'm retired, but if I wasn't, I'd get fired because I spend all day reading this forum.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
Thanks for the quick response! I think I'm going to hold off for now. I looked at CorvetteMods, and for some reason they have really jacked up the price @ $249, when you can purchase it directly from RPI Designs for $199.
I think I'm going to wait to see how loud this is before I go after it.
Thanks again for your help! This forum is an awesome place for answers and to just hang out. I'm retired, but if I wasn't, I'd get fired because I spend all day reading this forum.
I think I'm going to wait to see how loud this is before I go after it.
Thanks again for your help! This forum is an awesome place for answers and to just hang out. I'm retired, but if I wasn't, I'd get fired because I spend all day reading this forum.
After copying that link I found several spots that had the NPP in a box for $200. That's why I priced it at $170 (85% of 200). I believe I bought it from Southern Car Parts. I remember waiting on it for several weeks too.. Mine is available for immediate shipment.
Race Director
Joined: Sep 2009
Posts: 11,349
Likes: 2,443
From: Eastern
Thanks for the quick response! I think I'm going to hold off for now. I looked at CorvetteMods, and for some reason they have really jacked up the price @ $249, when you can purchase it directly from RPI Designs for $199.
I think I'm going to wait to see how loud this is before I go after it.
Thanks again for your help! This forum is an awesome place for answers and to just hang out. I'm retired, but if I wasn't, I'd get fired because I spend all day reading this forum.
I think I'm going to wait to see how loud this is before I go after it.
Thanks again for your help! This forum is an awesome place for answers and to just hang out. I'm retired, but if I wasn't, I'd get fired because I spend all day reading this forum.
Last edited by 4SUMERZ; May 29, 2020 at 06:47 PM.
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
If you have the stock exhaust manifolds and cats, it won't be too loud running around with it open. It gets loud in the open mode when you add long tube headers and delete the cats. Ain't retirement grand!!
After copying that link I found several spots that had the NPP in a box for $200. That's why I priced it at $170 (85% of 200). I believe I bought it from Southern Car Parts. I remember waiting on it for several weeks too.. Mine is available for immediate shipment.
After copying that link I found several spots that had the NPP in a box for $200. That's why I priced it at $170 (85% of 200). I believe I bought it from Southern Car Parts. I remember waiting on it for several weeks too.. Mine is available for immediate shipment.
If its too loud, I'll probably hit you up for it later, if you still have it.
Thanks, again.
Thread Starter
Instructor
Joined: Apr 2020
Posts: 127
Likes: 84
From: Dallas. TX
Stay away from buying anything at Corvette Mods. They "used" to be a Corvette vendor until they got really bad reviews, bad service, terrible customer relations, took forever to get the ordered parts, etc. etc. They are all over the Feedback and transaction section in a bad way.
Thanks,