Alright guys, another quick question. Right now I have a corsa cat-back exhaust installed on the 5.3. I'm about to install a turbo kit with a 4 inch downpipe. I think the corsa is 3 inch? pipe. I really don't want to sell the corsa, but I will if I have to. I want a sort of at least quiet exhaust, like the corsa provides, but I don't want to sacrifice power or building boost and what not. That's why I'm bringing up the cutout idea. So is it worth it? 4 inch cutout? Would I just tune the truck with the cutout open then open and close it as I please? Or would the best option be to sell the corsa and just get like a diesel exhaust?

 

I highly recommend one for that setup. Tune it with it open. It wont make as much when closed. Since you have the cutout, you can keep the corsa.

 

I miss my old Corsa catback dearly, but apparently they don't hold up well to the increased exhaust pressure associated with FI. Not to mention it's only 3". So I sold it for a full 4" setup. The cutout will definitely enhance performance, but it will sound like **** and rattle the cab like mad due to it's location. So I just stuck with full 4" straight thru exhaust. It's a compromise.

 

true, didn't think of the vibration in the cab. how loud will a 4in exhaust be? 4 inch diesel muffler or what?

 

Im running the stock catback with my turbo. Its really really really quiet

but with a 3.5" cutout it does get extremely loud and boost goes wayyy up casue my lil 38mm wastegate and i put it in the wrong location.

I tuned mine closed.. then opened it and its not lean from 0-6psi.. only 11.9ish, im commanding 11.2

 

i've been thinking about just a duramax 4 inch downpipe back exhaust from like MBRP. Would this just be overkill? i would think it would be a dog out of boost

 

That's the same kit I run. The muffler that comes with the kit is worthless though fwiw.

And with a turbo the less post turbine resistance the better, meaning bigger diameter and shorter length of piping.

 

do you have yours dumped before the axle, or full length? how does it sound? any drone?