Thanx, i think i figured it out. BOV are important in the job they do, whether you have a stock one or spend money on an aftermarkert one is personal preference. Ok heres another question for you all while im on the topic. My stock boost is set at 7psi ( for now anyway ), the aftermarket BOV i wanna put on is from a m8s R34 which was set at about 15psi, so the question is: Can i just wack on the aftermarket one and it will be ok or do i have to adjust the BOV so it works with 7psi. This may be a silly question but does the amount of boost make any difference to the air pressure left in the piping when the throttle is let off??