4 inch exhaust on a 3.0 duramax

[davidr83]

Just installed a 4 inch filter back exhaust on my truck. I ordered a full turbo back kit for a 01-06 Chevy/GMC  2500 with the Duramax. I knew going into this that things would have to be modified for this to work.

 

I started the exhaust right after the cat/flex joint where the stock exhaust runs to the back of the truck. I cut the stock pipe about 2 inches back from there and then used a 3-4 inch adapter from walker. Then proceeded with different pieces running it in pretty much the same fashion as the stock pipes and dumped it after the axle with a 5 inch tip. There was alot of pipe left over too should I want to change it. Also, At some point when all this corona stuff is over I will take it to an exhaust shop and have them lift the rear part that goes over the axle a few more inches so I can drop the rear to be level with the front. Right now I'm pretty sure the axle will hit/rub the pipe if I dropped it since it looks and feels like about 3 inches of space between them currently.

 

 The sound... Well it didn't change nearly as much as I had hoped but it did give a tiny bit more bass from the exhaust but not any extra volume. I expected that part going in. Nothing hits or rubs anything and you wouldn't really even know it's there if you had never been around the truck before. 

 

Before and after video coming asap

Edited April 21, 2020 by dram1983361

[davidr83]

 

 

[Black02Silverado]

Opening up the exhaust on a diesel will really wake it up.  The only problem is the DPF.  Anything after that will help, but not as much as getting rid of that restriction.  Diesels really love to breath.

 

When I put a 2.5" exhaust on my 91 Jetta turbo diesel my boost went from 9psi up to 14psi just from adding the exhaust.  I could feel the difference as well.  Of course it didn't have any emission crap on it.

[davidr83]

100% agreed! Unfortunately we might never get to see how much, if any, these new filters/emissions equipment may be holding back this little gem of a motor. I wish I could rip it all out so I can hear some spiny, whirly sounds from the turbo

[pewterliftedz]

These 3.0s don't have any mufflers on them from the factory, at least mine with the dual exhaust doesn't.  They're so dang quiet because of all the emissions crap up front, that I guess they didn't have anything to muffle haha.  Did your factory exhaust have any cooling fins on the exhaust near the tip?

Edited April 24, 2020 by pewterliftedz

[davidr83]

It had the resonators/fins or whatever they are in the back part where the pipe comes back down over the axle on the stock pipe. And you're right the diesels don't have a muffler from the factory and are still too quiet for me