I have a buzzing noise coming from the passenger front location of my car that only sounds when I am off the gas. At first it sounded like a real small exhaust leak coming from the downpipe/cat areabut isnow getting louder only when engine is NOT under load. When I have the hood popped and listen for it over the turbo/ leftside area of my engine and manually rev the engine I can almost pin-point the noise in the turbo; could it possibly be a bad bearing? This is my first turbo car so I do not know what symptoms or sounds one makes when going bad. The noise also can be related to a loose timing chain which could also be the problem; possibly bad tensioner??...is that a typical problem in a high mileage 1.8T? If so, I could very well relate that problem to inconsistent power levels that is apparent day to day. Wouldn't that noise be heardin the rear of the engine rather than the left side if it wasthe tensioner? Any help would be greatly appreciated, thanks.

Only mods done to my A4 B5 1.8T 80k Tip: is K&N drop-in and 710N DV.