exhaust rubbers keep on breaking

Hi,
I have a stainless back box on my 1.3. It is probably quite heavy compared to standard.

Since September I have had 2 original type mounts and one o ring type mount. All of which have broken. Only the mount closest to the back of the car is breaking.

Now on my second o ring mount. One of the issues I can see is that the mounting point on the exhaust is flat and a bit larger than the mounting point on the car which is curved.

Does this sound like the issue or are there any better mounts that I can use like the power flex ones?
Cheers!
Rob

Hi Rob, can you post some pictures of what you've got and how it's hung?

Edit; (The exhaust and it's hangers from the middle to the back)

you can get reinforced items from C&R, though mk2 golfs use the same type of hanger so polybush could be used.

or a real cheap fix is a jubilee clips round them.