Ok, I have absolutely zero experience with turbos, thus I need the assistance of more experienced members. I took a 2001 2.4L V70XC turbo out for a test drive the other day, when the turbo was spinning up it sounds like a siren once you let off the gas it stops. First time it happened I actually looked up to see if a cop was coming up from behind. Is this to be expected, or is the turbo on it's way out? The rest of the car was in fine shape, the only thing I am unsure of is the turbo.