It's probably nothing, but recently, whilst moving boxes around with my GTi with the rear seats folded doen and the car 'stripped' of clutter in the back, I've noticed a pronounced 'thunk' from the rear O/S corner when turning right over a bumpy surface or ridge. It sounds like something's knocking the floor, but I can't find anything loose in the back and nothing's hanging off. My first thought was a loose spare or maybe the jack's come loose in the spare, but surely (I figured) I'd get the 'thunk' over rough or bumps whatever I was doing. Trouble is I notice it now when all the seats are returned to upright and the parcel shelf's replaced.
Is this sound a well known ominous sign for something? The car's just passed it's MOT and nothing was noted then.
Outside of the car with suspension in normal setting (and with car as cold as possible) give the rear of the exhaust a good shake and see if it`s knocking against the body or floor somewhere.
Sounds like a possible case of knackered rubber mount-cheap and easy to sort out usually.
Yes, Ireckon you've probably got the exhaust crossbox hanger banging on the subframe or tailpipe, check the rubber hangers are all seated properly, they may have been dislodged during the MOT.