My truck can just barreeelllyyy max my 35 PSI boost gauge. My truck with a stock torque convertor would make less boost; my truck with a manual would make more boost but I don't know if anybody could wait long enough for the turbo to spool that much before shifting.

My fuel pin is still stock, however... A tight driveline with a maxxed fuel screw and a chopped fuel pin probably could get up to 40, and anything over 35 is in danger of popping the headgasket. Although, the majority of headgaskets are fine at 40 PSI, and that was considered the max safety level for the stockers for a long time until a few started failing at 35PSI over the past couple years... I think that the stocker headgaskets around the country are getting weaker now that they're 14-18 years old...

I'm still running stock intake and exhaust too... A BHAF and 4-inch downpipe would reduce boost a bit.

Another thing is that, without an intercooler, your EGT's are going to prevent you from running 35 PSI + for very long. An intercooler will reduce boost, but the reduction in EGT's is the really nice part.

And there are a lot more economical options for intercooling than getting a finned model custom made.