I was stopped 3 times in the same year in my work van by VOSA. On the third time, I actually told the person "this is f***ing ridiculous!"
No idea what the outcome would be of having illegal parts or emissions though.
i think you are alright as far as 'illegal mods' are concerned in the UK as long as it MOT compliant
the lack of cat and emmissions is the conecern will do some digging
edit
lack of cat is an mot fail and roadside emission test fail will cancell your mot so will need to get it rectified and retested
Last edited: