Alright peeps. Haven't been on here in a while mainly because I've just been too busy and burning the candle at both ends lol. The car in question is an A3 2.0TDI 140 (BKD). Last week I was driving home with the window down and noticed a bit of a whistle from the turbo at just under 2000revs to about 2400 revs and then it dissapears. I've done a quick search on google where I've read that it could be a small boost leak or the turbo is failing. My mate who studied car mechanics at college (but threw in the towel after a year) reckons that is the normal noise for a turbo diesel to make? I did notice the other night however when one of my neighbours drove past my house in his A6 TDI that it was also making the same sort of whistle (whistling for a few revs then dissapearing). The whistle cant be heard when the window is up, only when the window is down. Can anyone on here shed any light on this?