got loud rattle from somewhere under the seat towards rear on S3 which has got progressively worse. Sounded like a loose or bust spring but all ok when stationery, rattle is only when moving. All seems solid nothing loose but there is signifcantly more play on back UJs compared to front that is solid. The rattle is more then you go over a bump but always when driving, anyone think its the UJs or should i be looking some other place?

Exhaust pipe vibrating against chassis?, maybe a worn exhaust hanger?