MaineDoc

Has anyone added a dual mode exhaust system (GM) to their Corvette. Mine came with most options but this and I have thought about having it installed if possible and the price not crazy. I don't want some aftermarket system like Borla. I see these put on at Carlisle and they sound great but that's not what I want. Bill

Top_Fuel

Yes...lot's of people have done it. I'm in the middle of a dual mode exhaust install right now.

You can buy the dual mode ("NPP") mufflers from a forum sponsor GM dealer for about $1300. Or you can keep an eye out for a pair of used mufflers on the forum, Craig's List, etc. Expect to pay about $600-$800 for a used pair of mufflers. They will bolt right on in place of your existing stock mufflers using hand tools. There's nothing to cut or weld. Or pay an exhaust shop $75 to do it.

You will also need an NPP "retrofit kit" for controlling a vacuum supply to the mufflers. Two popular options for doing this are this one or this one.

Note that the muffler pipes are slightly different between 2005-2008 and 2009-2011. So the easiest thing to do is buy the mufflers that will work directly with your year C6.

BAMAGOLFER

It's been done with alot of happy customers.
I'll be doing it soon, going to pick them up this weekend.
It sounds great. Be sure to get the NPP in a Box for remote operation.

HarleyB

Just something to consider: the GM NPP exhaust has smaller quad tips, lots of hardware “junk” (visible flaps & valve actuators) and big painted mufflers exposed from behind, and adds only 6 hp…

while for the same $$$ you can get larger tips, hidden hardware and mirror polished Stainless Steel mufflers, and up to 19 hp from a dual-mode B&B Fusion system. IMHO a better deal.

FTW!

JPN7075U

I bought used NPP's and never added the vacuum lines. They default to open and I like the sound. I do have partial hearing loss from jet engines but my wife doesn't complain about them either. Compared to my mustang GT with SpinTecks the Vette is silent even with open mufflers. Huh did you say something?

JPN7075U

And the NPP's are way light. They look heavy but are light compared to the Corsa's I picked up. I was surprised that a GM muffler would be so light!

Top_Fuel

Agree with HarleyB on this point... IF you're going to spend $1300 on a set of OEM NPP mufflers, consider spending $1600 on B&B Fusion dual-mode mufflers. The Fusion Exhaust is sweet, but if you are on a budget, you can buy a nice set of used NPP mufflers and a retrofit kit for about half of what the Fusion will cost ($1600+).

FYI...if you're interested in the Fusion, someone has one listed on the big auction site right now (item #200595842394).

For the OP...there is another option. You can go with Z06 dual-mode mufflers. Read THIS thread for details.

JPN7075U

I paid $700 installed for my NPP's. I got quality mufflers for a cheap price. I can still add the vacuum system to go quiet or just use the actuator collars on a long trip. I had a very expensive aftermarket stainless steel system develop cracks in my Viper and the manufacturer would not stand behind it.

Prostang4spd

I bought a used set of dual mode mufflers off a Z06, they had the 3" exhaust, the muffler shop I used just cut the pipes at the mufflers and welded them to my stock 2 1/2 " pipes, the mufflers are actually 2 1/2 at the joint where the pipes meet. They did a excellent job but said it was a struggle to get them welded on, no space, ordered the npp in a box so I can use it in the wife/without wife mode...but it actually sounds throaty just being open, all in all its costing me 700.00 for everything...can't wait to play with the remote, turning it off and on.. or... I guess its Open or closed...Also like the bigger 4" tips at the back...

RoadReady

Anyone know if the Mild to Wild control box is waterproof?
Thanks

Xtremespeed

From what I remember, no, but it installs near the fuse box under the dash so it shouldn't be subjected to water.

hanks10GS

I went with B & B Dual Mode Fusions about 4 years ago and I'm glad I went that route. Great sound and looks.

garygamble

I also did the BB Dual Mode. Better looking and sounds great. Not too loud in bypass and quite enough to carry on a conversation in my convertible at 70.

2008 Corvette

SPSandman

Interesting, so you can install the NPP mufflers on an existing stock exhaust and not have the switching system in place? So without the switching system, would it stay open... or is there a way to manually close it from the outside say before a long trip, and vice versa open it up before getting in the car?

I have seen a few NPPs for sale and tempted on grabbing a pair since I like how the NPP sounded when I saw it in person. Granted laserlemonta has MUCH more in the engine, but think it would be a good option. I would definitely look to add the switching control system to it at some point, and like the idea of having the ability to control the loudness.

feastersss

Has anyone ever installed everything required in NON NPP optioned car from GM to make OEM NPP mufflers work instead of using the NPP in a box?

jimijam

Please STOP referring people to businesses that are not in business any longer. That first link is as worthless as **** on a frog. They have been out of business for a long time, and for good reason. https://www.corvetteforum.com/forums...creations.html

07MontyRed

They were very much in business EIGHT YEARS ago when he posted that, so perhaps your criticism should be tempered.

Of course, why anybody resurrected an eight year old thread is a bit odd.

jimijam

Doh! I can't believe I didn't catch that. Normally I am on point. Must be the green beer I've been practicing with all month leading up to the big day on Monday.