My S3 has always had this since going to Revo Stage 1, but now I've just fitted a ITG CAI (See here: Silky's S3...) its now much louder (to be expected) and just though I'd check with your guys.
So on WOT or 80%+ (I.e not when letting off the throttle, so its not DV noise (I do get this though, but thats nomal)) I get something that sounds like turbo flutter/modulation. It sounds like the turbo is pulsing on and off very quickly, with a air sounding 'psst' noise. It has no effect of performance and the car pulls strong all the way through it. It seems to happen between 3k to 4k and then stops.
Nomal? I seem to remember Awesome GTI saying this was normal when the car went to S1 due to the higher boost pressures, but now its a bit louder just thought I'd check!
The car pulls well strong so I don't think anything is amiss!
Also - on that note, anything I can log in VCDS to check the boost is ok etc? Requested vs Actual? Any advise?