I recently bought a 2001 S4. It has 91000 miles on it and I'm worried
> that the turbos might go soon. Is there any sort of warning that I can
> look out for? Do the turbos make any strange noises when they start to > fail?
>
> Also, I don't know if the timing belt has been replaced. Is there any
> sort of warning for that as well?
I don't know about the turbo but if the timing belt goes, the only sign you're liable to get is the delightful - and expensive - sounds of valves colliding with pistons.