Hi all, fitted a full exhaust system to a mates WRX hawk today. Took it out for a spin and I noticed there is a hissing noise when under boost... Does do the usual dump noise when you let off throttle but the hissing worries me that it is wasting boost pressure..
I asked my mate and he said it has done this since he has had the car (about 6 months)
Is this normal operation on a vent to atmosphere dump valve? Seems a bit odd to me.

I have told him to change it back to a OEM recirculation valve but he sort of likes it.
Is it worth getting new springs and a service kit for it?

Cheers.

 

Imo.... chances are your still on a maf sensor so just save the greif and go back to recirc.

If youve gone mafless, and want to keep the forge dump then buy a spring and shim kit and up the spring incrementally till your happy.

 

I totally agree.... I have a recirculation valve on my own hawk making good power on an uprated turbo. But as I said, it is not my car so not my decision.

Still has MAF and I have put a mild tweak to the ecu map and I think this had made it louder/worse backing up my theory of it leaking.

I have read on various forums the springs on these dump valves only last so long.
Logically if the spring is worn it would have issues holding the pressure back? thus allowing it to make the hissing noise losing boost pressure?

I am trying to convince him to get a recirculation valve but if he wants to keep the Forge BOV I at least want it working correctly for him.