+1So I have seen it time and time again on the Forum when someone says "what BOV do I get" and everyone yells that they shouldnt do it. I have also seen when someone that has a BOV goes and says, you guys are pansies and ends up getting butt raped prison style by everyone. What I have to say is based on experience, and also by fact because I just tested it:
You guys can yell and scream about it after, but I am going to make a comparison, about 100% recirculation Bypass Valve, and 100% atmosphere Blow Off Valve. Dual stage ones that can go 50/50 I will not comment on because there is such a variation of how they work, and they are more of a compromise in sound and design. So let me write it as a script.
BOV: Fact is, with a direct vent to atmosphere it will release pressure faster becuase there is no restriction. Yes of course you do create an audible sound.
BPV: I cannot vent pressure as fast as a BOV because I have to send air back to intake tube, but there is a reason I do it. When I open, I create a loop around the inlet and outlet of the turbo, so when shifting, the air can freewheel through in a circle and let me run in neutral. Its not much, but the MAF sensor doesnt sense any more air ingestion, and doesnt compensate and run rich for a second and make the car jerk.
BOV: But wait dude, I make a PSSSSSHHHH!!!!
BPV: I know you are all about that bling bling, but I was designed for a reason. Oh and here is something I bet you didnt know. When you step on the gas at idle or at no/low boost I actually open, and let air flow through me backwards!!!! Now not to say anything nasty about me, Yes I do take it both ways.
AFblueSV1k: See folks I actually did a quick test, in my garage with my STOCK BPV and a Mighty Vac brake bleeder. Putting anything more than 10 in.Hg on the vacum line, overrides the spring pressure, so valve is sitting neutral, not open nor closed, and can be pushed. So that means if the past of least resistance is in the intake through the bypass line, into the intercooler, and into the manifold. So at times the your car will run naturally aspirated and bypass the turbo completely untill the turbo picks up and can take over at 0 psi, because WOT in a Naturally aspirated car is 0psi/0in.Hg. At these times, the turbo is actually a resistance in the induction system, so it was designed to be bypassed and increase no/low boost throttle response. This would explain how some get compressor surge and reduce throttle response with BOV.
Final verdict: The BPV is better for a reason, sorry it doesnt make the Pssshhhhhh!!!!!! for some of you, but it does actually run better on the car. So now go and complain to the Subaru engineers that designed the WRX that aftermarket BOVs dont work on your car and they shouldnt have spent so much time desgining the best car that they could for you.