i drive a 88 turbo supra with shimmed wastegate with 4 2mm washers ::i would say around 9 or 10psi:: on it,gutted d/p and k&n drop in filter i raced a 85 corvette with a lt1 swap from a 93 transam motor with 6 speed tranny he has headers,k&n filter and 3 inch flowmaster exhaust...1st gear and 2 gear he pulled 2 car lengths but when i hit 3rd and 4th neither one of us could pull on the other...its a lose but it was my first race in my supra