John, your car will be absolutely fine when taking it for the MOT if you get the M260 upgrade. If in any doubt just flash it back to the standard map before the MOT like I did and it’ll be fine. I did this and it flew through. 👍🏻If I cancel my new car and keep the M235 my third service and MOT is due in January.
I’ll probably get it done just after Christmas though; however the question is should I take it up to 260 before the MOT? Slightly apprehensive after what @antl76 said about emissions although to be fair he was referring to his Mk7.