They estimate 35psi before studs and fire rings and all but each engine handles it differently. My dad had a 94/95 second gen running 40psi without issue. Currently working on a friends 92 first gen and he was seein 28-30 and belching black, i changed so stuff around and what i changed increased his airflow capability and dropped his boost to 22psi WOT and cleaned up his exhaust, still have more to do. I am also building a first gen engine out of a 92 and switch to a ppump and doin alot of other things like twins and i'm setting to try and be around 32psi but making alot of cfm