Originally posted by Petri
Still how do I know the difference between BOV's, Like can I just go to a web site and pick out any BOV, if so then why should someone spend $300 for a name brand and not go on ebay buy one that looks the same on the outside for $30-80.00? Isn't there different springs, How does the BOV know when to let air out. My friend had a Turbonetics BOV and we mounted it on but when I hit the gas to hear how it sounded (car in park) the air came out the inlet side of turbo and I know thats not good, so there has to be some kind of set up when buying a BOV? ?

You hook up a vaccuum line to the BOV, when the throttle plate shuts the vaccuum in the intake manifold opens the BOV. The reason people SHOULDNT buy knock off ebay brands is quality. Crappy blow off valves leak air and usually ddont expel the air in the charge pipe fast enough, this causes air in to go back towards the turbo and create compressor surge.

Turbos dont build boost in park.