yeah its pretty well covered in some of the threads mate......i personally have been adviced by some of the guru's of imports that on a stock RB25 turbo dont go past 12 psi....12 psi is the safe boost level....anything above that will reduce the life of the turbo big time.....i have mine on 10psi on a r33 s1 and i reakon that is plenty of boost for me.....