There is no exhaust gas check other than a visual its not burning oil. As long as the cans have the baffles in you will pass the MOT. Some testers may comment if they are too loud and may put an advisory on it but it will pass.

I had this dilemma but mine were the louder CCC stubbies so I took them off for the MOT as I was certain I would get an issue as I know the guys there as they are a main Yamaha agent so did not risk if for a 10 minute job.

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