Dump valve noise
 

Right, I'm wondering if this is the start of a problem with my car or if it's normal. I noticed earlier that if I lift off from full throttle I can hear a noise like a dump valve opening, even though I've got the OE recirc valve. It's not particularly loud so it's possible I've missed it previously but I've had the car a couple of years now so I'm not convinced.

Any thoughts?

I have the Forge MY97/98 recirc plumbed into my set-up, and it also makes a (satisfying) rapid #pee'owwn#-type whistle, when coming off the throttle from high boost -- despite the air being directed back into the intake hose i.e. no air escaping to atmos. Obviously.

Do you normally drive with the radio/music on and haven't really noticed it before?

Obviously, check the security of all your clips for the turbo hoses... Esp the recirc hose's ones, 'twixt dump valve and intake.

Also check all hoses for splits.

This was my initial assumption tbh but I do drive around with it off from time to time.

Check hoses etc i fitted an STI intercooler to mine and after it was making a weird sound, i pulled it all apart and noticed there were 2 gaskets on the Y pipe on one side. Only small thing but air was getting out.

I can hear mine, a Forge recirc, but the car has an induction kit and is MAf-less.

Yes, I also forgot to mention, mine has a cone air filter too - so that acts as a route (albeit baffled) for some of the sound to escape to. Neil, have you got an open air filter set-up?

Mine did this for a while, turned out it was the gasket on the rear of the valve was broken, got a new gasket and refitted the recirc valve and it fixed the issue.