As of yet there is nothing stated in the MOT testers manual if you want to 4x4 cosworth your focus with 200 or 1000 hp you can end of as long as everything testable on the car passes as with a normal MOT test the only hurdle that may affect you depending on year of focus you are using dependent on year will either be 0.5 or 0.3 co limits
Hope that helps.



Regards Doug .