My car has developed a chattering noise, like a rattle infact from the rear of the car which seems to be coming from the exhaust system. I've had it at the garage and there trying to say it's normal but I'm not convinced. It happens between 2200 and 3000 revs in any gear. It doesn't do it when stationary and revving. The mechanic said it might be something to do with the waste gate. He got this info from the VW bullitin board so it must be a past reported problem. Can anyone confirm this sound should be there or not before I raise hell. It is very obvious to a trained ear and any feedback would be appreciated