prob when reversing

[sionowz]

hi, when I reverse my car has gone increasingly loud... it's making what I can only explain as a 'chuk chuk' noise...... ..similar to a train... any ideas???

 

[f1nn]

Exhaust vibrating on rear beam?

 

[sionowz]

could be..I had a custom cat back put on a couple of months back...and it did starting knocking when just starting to take off and slowing down...think its the centre box on a sump guard or heat shield or sumin...but this new noise has just startd...could the exhaust be getting worse....??