billsblue73

I'm installing a LS3 525 and 6 speed in my 1973 Corvette. I would like to be able to control the exhaust sound as with the dual mode in the C6. Has anyone done this before and are there any suggestions?

fleming23

This is really no different than a cutout to open headers. The issue is you'll need an actual muffler with a bypass and valve. You could try to modify a c6/c7 stock exhaust and I think could be made to work. Then just wire up a 2-way toggle switch inside the car to open or close the valve. The issue is, you'll need to fabricate all of this, nothing is just going to bolt on off the shelf.

Looking at my C7 Z06 take-off exhaust, I think it would even fit in the rear cavity of a C3 but the mufflers are rather large.

Having previously owned the 525hp LS3 in my 71, it really isn't very loud, even with ARH Headers and a full Magnaflow exhaust.

MelWff

here is an alternative solution, exhaust cutouts
https://www.summitracing.com/search/...rder=Ascending

lionelhutz

The C6 NPP is a vacuum exhaust valve controlled by the PCM. You can get aftermarket vacuum exhaust cutout valves. So, you could build whatever exhaust you want and use the C6 NPP vacuum controls to operate it. Basically, it opens at a certain throttle and rpm which can likely be adjusted by tuning software.

Kevin BC

Here are another couple of alternatives. I have been looking into this also, but no experience with the actual products.

http://xforceusa.com/products

http://www.waldronexhaust.com/driver...ledexhaust.htm

Kevin

lionelhutz

Thinking about this more, the NPP output from the PCM is likely just a solenoid driving signal. So, it should be very easy to use the PCM signal to drive a relay instead. Then use the relay to operate electric cutouts. Probably easier than building a hybrid vacuum electric system.

ajrothm

Borla also makes a “NPP” style muffler for C6s that is much smaller then the C6 NPP system. With vacuum operated modules, it would be easy to make it work in a C3 with either a vacuum switch or 12v solenoid. Fitting the muffs would be the toughest part.

There are several ways you could do this tho...From either using electric cut outs to atmosphere or a muffler with the bypass in it like the old warlocks.

Cutouts pretty much sound like *** though. I’d much rather have the exhaust going thru the open side of the muffler, it still takes just a bit of the crackle off of the sound.

I’ve had cutouts on 2 different cars and other then at the track, they always stayed closed....it just sounds too shitty to me...

jim2527

Someone did it with Camaro mufflers..

https://www.corvetteforum.com/forums...-on-my-c3.html