ok first off after doing my tbelt, i get a high pitch sound from the engine bay when i start my car now it has a high pitch sound almost a metallic whistle. [mid tbelt job after it was done, before putting radiator/cooling back in place, it was VERY loud, the only time it was any louder then it is currently]

but the weird thing is it doesn't happen every time, depending on the weather it doesn't always happen. NOT necessarily *extreme* hot or cold but when its like perfect weather outside(could be warmer or even cooler days) it wont make the noise. and it never happens if the car is warmed up, like if i drive for 5minutes go to the gas station, come back out and start it again it wont happen. im figuring a turbo rebuild/replace is what this means.

also, it goes away after the car has idled for 3-5mins, dont hear it when driving(unless i take off while its still making this sound it may last for 3minutes or so). my other thought is bad DV. though still no hesitation nor lack of power, ever.(i have posted about 3 codes that i have been shown with cel, 02 sensor, 2ary air pump and temp sensor)

Now for my second issue, recently i noticed a medium-loud echoed buzzing in what seems to be the right rear, i figure wheel Bering maybe, the sound only happens at 50+ mph. no drivetrain, or wheel work has been done as far as i know. braking nor increased/decreased accelerating has any effect/change to the sound, just a speed of 50+ is when it can be heard.
(searched forums for this, found nothing of REAL use to me.)

of coarse all insight questions/comments are much appreciated.

2000 ATW 1.8t quattro manual. 102,XXX miles

thanx!