can anyone shed any light on a rasping noise from the exhaust under acceleration// sounds like the exhaust is leaking but cant find the leak at all the joints and no holes???? this is not the wastgate chatter you hear when letting off throttle// just wondered if there is a common weakness in the cat breaking up or if its something else and im not thinking out of the box. any help or experiences would be appreciated as i dont want to have to remortgage the house to take it to the audi dealer!!! im new to audi iv been a toyota nut for 7 years and fancied something different. thanks