67who

is this right? exhaust mode came on my c7 conv. $1199 the tail pipes have butter flys in outer pipes but the middle pipes are fake.want have info before calling dealer

Higgs Boson

why do you think the middle pipes are fake?

the middle pipes move quiet exhaust.

the butterflys on the outer pipes open up to free up flow for more noise and 5 HP.

FYREANT

yep that sounds like the NPP exhaust to me.. except the middle pipes are actually functional..

RonC7

Check these links for an NPP schematic and more info / options:

https://www.corvetteforum.com/forums...ust-issue.html

https://www.corvetteforum.com/forums...ck-result.html

Also search for NPP. There are lots of threads and lots of confusion.

Modshack

Not "fake". They exhaust 100% when the NPP valves on the outer pipes are closed...Inner pipes (green) are perforated.

Theta Pic:

sstew

They have integrated sound control valves in the exhaust system just ahead of the mufflers on each side. They are supposed to modulate the sound in four cylinder mode to make it more pleasing to the ear. How affective they will be is probably subjective, and will cause more controversy on the forums.

These are not to be confused with the valves in the muffler outlets that come with the dual mode NPP exhaust option. With NPP you will actually have four valves; two before the mufflers and two after the mufflers. All are now electric as opposed to the vacuum operated valves used with the previous NPP option.

The two valves before the mufflers are to make a more appealing noise (sounds like a M model Farmall tractor) in 4v mode and they are there with or without NPP.

Read more: http://gmauthority.com/blog/topic/c7...#ixzz3DaothCyS