[kamilk69]

well i run 8-9 psi but around 6000 - 7000rpm it spikes to 12, i say 12 is ok.

but you have to remeber that psi means nothing. 8 psi on a small turbo will produce a different power output than a large turbo at 8psi.

you cant measure in psi you have to measure hp. i could run a small turbo at 16psi and produce the same hp as a large turbo at 8 psi. it all about how much air your turbo can flow.

the safe limit for a stock zetec i think is around 250hp, then s*** starts to break,