I have a 2001 STI full metal jacket job with all the trimmings, my wife drives my old 2001 WRX, she wanted it to make a noise like mine so I bought and fitted a turbo dump valve........... no noise! what have I done or not done please?

A dump valve will cause your car to waste gas and run rich between shifts, but you probably know this.  

 

Is there an adjustment on this valve, maybe it is too tight?  Too tight will cause compressor surge and damage the turbo.  Too loose and it will bleed boost, losing power and running rich.

Thank you, but no there is no adjustment on the valve.  It came from a RB270 which had been rolled to death, after it had been mapped up to 320 bhp.  The valve itself was only three weeks old. My wifes WRX is the baby one with 225 horses, will it be developing enough turbo pressure to throw the valve? Am I just better telling her it's not possible? 

I think RB270 is similar to the 2002 WRX STi here in the states.  I am using stock regular WRX bypass valve on my EJ20G at 19.4 PSI, but I did need to modify it to hold more pressure.  The STi one is designed to hold more pressure.

 

This valve must be aftermarket though?  The STi here has a bypass valve and not a dump valve.

 

I know most aftermarket valves are adjustable so you could always get a different one.  But really I don't recommend a dump valve at all as it will reduce your performance unless the car is really tuned for it.  They do sound cool though!