i think maybe this has something to do with the new sva testing by the dvla? kit cars are the worst affected, the more oem parts your car has the less likely you are to cross their line. so a golf retro fitted with a g60 engine would be ok as the model came fitted with that engine. put a toyota supra engine and rwd transmission in it and you’d have some explaining to do.. check out practical performance car magazine some of the back issues have articles covering the new legislation.