Did you have head studs in your IDI? I was making 15 psi w/ H2O - meth going & people told me I was gonna pop a head off if I went much higher in pressure.
No, I never did anything with the Head Studs. I could [get] 20 lbs of boost but I never made the 'ol Boy Hold it, because of EGT temps.. and the Head pop issues. I could & would, throttle 20 psi to crest a hill or complete a Pass.. that's about it.
Had the ATS Turbo set up and Pump tweak on'im for about 175K... 'til I sold it. He was a Hand Full with a 11' Lance on the back & Metro in tow.. had to keep a Constant Vigil on traffic, terrain, gearing (had a GV splitter), rpm's, egt's, boost and engine temps.. lota fun tho.. kinda like driving my " OTR Big Truck".(at the time) he'd Git'r Dun tho.
Whooo.. go'n down Memory Lane here
I had very good luck with ATS's stuff. Good Tech service too.