I have 06 GMC LBZ with a deablo sport tuner, I pull a lot of heavy equipment. I want to upgrade the exhaust system but not sure what would be best, cat in or out and 4 in or 5 in, can anyone help

 

I am a Cummins dude but will assume that this knowlege will apply to a Max as well...the less the resistence the better.........someone back me up on this for the D-max though

here is some exhaust information in general that is very interestimg

https://www.dieselbombers.com/showth...ht=pipe+dreams

 

I'd get rid of the CAT unless you are in an area that requires visual inspections or opacity tests for emissions. 4" works just fine until you start pushing over 500hp at the wheels.

 

I went with 4" fromt he turbo back(so they call it). I would go catless

 

The biggest EGT drop will be from a Catback ya gain a little more losing the cat and if you block off the EGR, but you could set a CEL more likely if you do the cat and you will set a code if you block off the EGR. I would just cut out what ever you want muffler/cat and get some pipe from a muffler shop. The codes can be avoided with a Finger stick and removing anything other then the muffler could cause you some trouble at the dealer.

 

I went with 4" straight pipe egr blocked and fingered. It runs wel, without a load and ppe hot+2 level 3 at wide open my egts only go to about 800*.

 

Where do you have your pyro?

 

800 would be a post turbo mount

 

It is mounted pre turbo,this is a pic http://dieselplace.com/forum/uploads/CF8_installed.jpg

 

I think you have something wrong with it then because 800* is way to low. I wouldn't be surprised if you shouldn't be able to bury at 1600* pyro with the Hot. How many HP is level 3 and what are your cruising temps?