It is a 2007 wrx sti.l already have installed injen intake(cold air), hks carbon ti exhaust, and high flow cats

Well the Sti already has a blow off valve So why would u want to intall another?/?

Yes u can replace it with After market one which will probably be of a lesser quality but It will not add any performance so why?? If ur looking for the noise u can simply divert the air from recirculating to the intake, plug the intake & the vent the BOV to atmosphere.

Edit; Venting to atmosphere will not produce any loss of power or any change in the vehicles tune. The bov is only open when there is vacume after the buterflys & boost before them. (off throttle or durring spool depending how stiff the spring is.) durring this time the engine is either in F/C & not producing any power or it is just starting to spool in either case the recirculated pressure is in no way adding any kind of relevent pressure to the pre turbo intake track beacause the volume of air being realeased through the BOV is very small when compared to the size of the intake which is wide open to atmosphere via the air filter.

edit again; bypass valve is just another name for a BOV they r the same they both have preload spring & they both have a vacume port! & again Venting to atmospere should not affect tune because when its open u r off the gas which means the ECU is in fuel cut! & even if it was not it does not matter because the bypass valve just recirc is the air back into the pre-turbo intake which is not sealed to atmosphere it does not in anyway pressurize the pre turbo intake.

The first answerer is 100% correct. You should also note that if you follow his procedure, you will get a cool noise, but also a reduction in power.

Serene is mostly right.

The Stock valve on ur TMIC is actually a by pass valve.

An aftermarket BOV will only help u if u r running significanlty more boost than that stock BPV can handle ( l think the number is 19 or 20 PSI).

You CAN install one if u want the noise so that u can pick up chicks but u may want to take out the intake ''snorkus'' first. The ''snorkus'' is the part of the intake tract before the air hits the intake box (where ur air filter is). It is inside of the fender well & basically acts to muffle any intake noise. A lot of people take it off & report being able to hear the stock BPV.

If u do it the first answerer is way u may run the risk of running rich because the computer is expecting that extra air being recirculated back to the intake tract.

Actually, the first answer is incorrect. The stock STi (and WRX) come with a bypass valve, not a blow off valve. They both recirculate pressured air back into the intake for emission control.

l would not install a BOV (blow off valve) on a stock STi, as it will cause u to run rich between shifts, idle unevenly, & hurt performance. Most ''ricers'' do it to show off they have a turbo, but in fact, they actually r hurting the performance of their (great) car.

You should wait to install the BOV until you've substantially modded the car, including a new turbo, uppipe, downpipe, & intercooler. At that point, u will need the extra protection of a true BOV in conjuction with a reflash of ur car is ECU (computer) to handle the modifications.

zv