I first noticed this problem because my exhaust sounded like it was leaking. I decided to examine the problem
further with the car up on lifting ramps. The exhaust was indeed leaking - on either side of the rear silencer are exit pipes (which in turn lead to the tailpipes themselves).
On my car, the clamps used had weakened to the point where they no longer gripped the pipes sufficiently - the result was a slight leak, and the tailpipes had dropped to rest
on the cut-out on the rear clam. Not ideal!
1. Raise the car
onto axel stands, ramps, or a lifting bed if possible.
2. Remove the rear diffuser and rear undertray. Keep the bolts in a safe place!
3. Working under the car, examine the two clamps on either side of the silencer. You will see rust if they have corroded, and you should be able to physically move the tailpipes up and down in the hole in the rear clam. You should notice the movement on the clamps if you can do this.
4. Undo the old clamps from the silencer.
5. Buy some new, standard 45mm clamps from your local exhaust centre. These should cost around £1.50 each.
6. Before fitting the new clamps, smear a little exhaust paste into the join on each side to get a good seal.
7. Fit the clamps onto either side of the silencer, and finger-tighten the nuts to hold the clamps in place.
8. Center the tailpipes in the cut-out correctly (looking at the rear of the car), and get someone to hold them in place whilst you fully tighten the clamps. This will hold the exhaust in position.
9. Run the engine and check for leaks in the exhaust system.
10. Refit the undertray, then the diffuser, and you're all done!