Join Date: Dec 2002
Location: Denver Colorado
I agree with all the above also , but one thing you must realize is , a lot of the factory parts were designed with keeping the WARRANTY safe.
The BOV may leak or release too early , the ECU may run the injector cycles richer than it should , the exhaust is also severely restricted in an attemp to prevent overboost. Once you start replacing exhaust and intake parts , the BOV will be overun in very short order. That was a common problem on DSM's , the BOV would start leaking at like 9-10 psi , one solution was to put it in a vice and "crush" it so that spring pressure was greater.
I've done static (off-car) tests of the factory WRX BOV , and it starts bypassing at about 12 psi. Any aftermarket BOV is a good investment before you get too far with mods....................