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Probably is but Caterham calls it a bobbin
https://caterhamparts.co.uk/mounts-gaskets/1075-exhaust-mounting-bobbin.html

16883

I had this happen years ago on an old Caterham of mine where bobbins used to fail every few years. Took me a while to work it out. Whats likely happening to you is that your exhaust pipe is not...