What is the max boost on a stock 2003 HO Turbo with an ATS manifold and 4"exhaust all the way out and 51" Donaldson muffler. I keep reading that anything over 35# is bad on a stock turbo but I have mine set at 40#(Adjustable boost Elbow) and my EGT's are down quite a bit. I haven't experienced any turbo bark. I have read that anything over 35# that I'm just reading heat on my boost gage but when I adjust my elbow to 35# of boost my EGT's go up. I do think if I did have a modded tranny then I would toast my turbo but because that is still stock its helping my turbo in a way. Am I thinking way outside the box here ? Thanks Guys.

 

The max really wouldn't have anything to do with the mods you listed. The stock turbo is good up to 35psi. Anything after that it's just blowing hot air. It supposedly can handle up to 50 psi but again, you loose your efficiency after 35 so it's not doing anything to help hp.

With the stock turbo I frequently saw 42psi @ WOT and had no problems with it.

A modded tranny wouldn't help matters either. It would enable you to put the power to the ground without major damage to the tranny but, you can only put so much power out with stock parts.

 

Then shouldn't my EGT's stay the same at 35# of boost compared to 40# ? This is what I'm trying to understand. I can pretty much get on the highway at WOT until I hit the max 110 mph and my EGT's will never go over 1300 EGT'S but when I set my boost elbow to 35# I can only go up to 90 mph the I have to back off because my EGT's are hitting 1400 degrees. I'm sure you are right on the efficiency of this turbo but if 40#(more heat) isn't going to hurt the turbo that much then I more comfortable at leaving it where it is. It appears it still moving more air out or moving more air out quicker.Thanks.

 

Tri's stock turbo is not the same one you have on your 03. I had an 03 and you should definitely keep your boost at about 30 psi. It can take 35 but you're pushing hot air and your EGT's show that. You already have good injectors so save your coin and get a new turbo and built tranny. The truck will really run then.
Train

 

How do the EGT's show that if I run cooler at 40# then at 35# ? I get faster spool up,my EGT's are lower and it feels like I have more low end at 40#. This is the exact opposite when my boost is at 35#. I agree that this truck will go better with new tranny,turbo and I will also add a Smarty just for the finishig touch. I don't really care about the effiency so much as I just want to get aother year out of the turbo with bowing it up. Thanks.

 

I'm not sure why 40#'s is cooler then 35#'s of boost since both are out of the efficiency range. That part doesn't make since. I do know the life of the turbo depends on how your box ramps up the power. Your quad box from my understanding is very smooth....Ramps the power up where a TST box or some of the SMARTY programs really put the fuel out. I'll say this.... I wouldn't run 40 because I don't think the turbo is designed to run that high, but it's your call.