My friend just bought a 88 turbo II.I was wonderin what stock boost levels are and what is the most boost u can run on stock fuel.thanx

 

flubyux2 says:

7-8 psi stock
10-11 psi w/ no cats and free flowing exhaust

not sure how much boost the stock fuel system can support.

maybe Ryde will chime in...

 

5.5psi for S4s, 7.5psi for S5(not positive on the S5s).

As for whats safe, its not always going to be the exact same. Depends on condition of your fuel system(injectors/pump/fuel pump wiring). I'd say 10psi should be good for stock. Personally I'd get a fuel pump fist, but you don't have to have one. But to go over like 8psi you will need a FCD also, so you don't hit fuel cut.