Thanks. I guess it could be something that got left in there when it was assembled? Funny arrow part on it made me wonder if it was some sort of rubber seal.
It went in for its first MOT test today and passed, even with the loud exhaust. They tightened up the decibel laws in the UK this year.
The bike had the annual service last week and the dealer wouldn't pass it for the MOT because of the loud exhaust, so I took it to a specialist today who did!
@Jag. It was wet here today and the country lanes where I live were covered in water and debris, so she had a good clean up.