I was about to post same question m8 , mines is runnin 14 psi the noo , but gettin a new actuator on friday and may turn it up when fitting (slightly ) ,i have chip,cam,pulley,grs intercooler,mongoose, 156bhp@14psi@wheels,,rolling roaded 2 months ago ,, everythings sound with car , but hear lots of peeps wa 18psi and that ,, but how much bhp am a likely to get ? , and are probs iminent with a few more psi