20-25 stock

 

better to get an s300 turbo with a better wastegate and better flowing exhaust housing. There is no reason to turn up an hx35 to over 32psi as the air cannot get out easily. You end up with a pressurized box because the WG on the hx35 sucks (only wastgates 3 cylinders) and then it is further blocked by the back plate before it goes into the downpipe.

 

they say no more than 45psi with stock turbo

 

I'm supposed to be doing the head gasket this weekend (if I can find one), I have a thread right now going wondering if Felpro gaskets are acceptable substitutes for Cummins ones if you can't get OEM.. I am running the stock turbo at about 30-35 PSI, though I usually have to back my foot out of it if I have a heavy trailer and big hills.. if I'm not towing over 4 ton it's not a problem though. I am really looking for a SuperB turbo though so I can comfortably put 40PSI into it without it coming apart