I have just bought a MY94 WRX wagon and it has a greddy dump valve on it. It doesn't make a big hissing noise at all (thank god), infact I can't hear it at all. It has a bolt on it with arrows that suggest that you can adjust something by turning this bolt (the release pressure perhaps?). Can anyone enlighten me on this.
Also I am having an overboost problem like I have a dirty wastegate solenoid. I will clean this tomorrow but wondering if the dump valve could be messing things up.
One last thing, the dump valve has a smal nipple coming of it's side that looks like it should have a tube connected to it. Is it normal for there to be no tube there?

 

that nipple should have a pipe going to the vacuum pipe

 

Thanks, will try to locate hose tomorrow.

 

Any tips on which pipe dump valve should be connected to. Probably obvious but no harm asking eh.

 

It will go on the pipe between the turbo and intercooler (not the ine that runs from the intercooler to the inlet manifold)

i have a blitz blow off valve with the same sort of adjustments, it only really changes the noise that the valve makes, it tightens the spring inside the valve making it open quicker for a more harsh noise, or looser for a softer noise.