All, I'm new to this forum but have been browsing for some time!
I have a white 57 S3 and love it! I've been hearing a strange noise for the last few weeks which I'll try and explain but the car is running perfectly, turbo is coming in fine and no warning lights etc.
The noise only occurs when I lift of the throttle only after 2000RPM i.e. only after the turbo kicks in. Now the noise isn't really a whistling noise or a 'whoosh' type noise, it's more squeekier and sounds a bit like a cat purring - sorry it's the only way I can describe it.
I've limited knowledge but savvy enough to carry out the basic things, so I removed the engine cover, MAF etc and upon revving the car hard on standstill, you can notice the noise very clearly around 4.5-5.5k revs. This suggests it's not the air filter which someone advised it could be!
The noise appears to be coming from the top of the engine i.e. on the windscreen side. I checked as many pipes/hoses as I could and could find no leaks. If there were leaks I'd suspect low boost etc?
Sorry for the long post, just trying to give as much info as possible! Has anyone experienced this problem before? Does it sound like a DV issue?