You never said what vehicle but I'm going to assume its a Avalanche? I have an Av also and for as big as it is there is really not a lot of room under the truck which really limits the muffler and exhaust configurations.

Personally I think you should wait for the supercharger before installing a 4" exhaust. How do you plan on running the exhaust? dumped? single out? I cant imaging being able to snake a 4" pipe around the rear axle to exit behind the tire, unless your Av is lifted.

Below are my suggestions on Mufflers, if you are a Amazon prime member they have free return shipping....clamp the muffler on the truck, go for a spin around the block, if you don't like the muffler clean it up and ship it back!


MagnaFlow 12772
Hushpower 14020100

Walker 4" in/outTurbo Mufflers

 

I run a borla proXS and longtubes. It's quiet when cruising but sounds badass at wot.

 

Chris what is your exact setup? And whats your offsets on the inlet and outlets?

 

Ended up going with a solo performance mach muffler... Sounds amazing... Will post a video soon

 

Nice, post the video up and I will check it out.

 

ok here is some exhaust comparisons for you all...

stock manifolds and stock cats... just a custom stainless cat back 3 inch with borla XR-1 5 inch round case muffler...

05 avalanche 5.3 with 3 inch stainless borla XR-1 exhaust - YouTube


full length headers with ORY into the same exhaust only with an 18 inch case bullet resonator in front of the XR-1

borla xr-1 with full length headers and no cats with bullet resonator - YouTube


and now finally i have a solo performance MACH straight through muffler on there... MUCH quiter but still has a deep nasty tone once i get into it. SO FAR I LOVE IT!!!!... i have only 250 miles on the muffler now... and i still have the bullet in front of this muffler but i want to wait till about a 1000 miles to let this muff break in and see how loud it is before i decide if i want to take the bullet resonator off to make it just right...

avalanche with solo performance MACH exhaust with full length headers and no cats - YouTube