Ireland might be a bit different from most of the EU in not having a lot of vehicle regulations, even in the '80s there were a hell of a lot of people in rural areas that didn't have a driving licence.
This week local politicians in Co. Kerry called for a relaxation of drink driving laws, perhaps to help stimulate the local economy.
On the opposite side of the lassez-faire Irish attitude is the Germanic-strictly- adhering-to-manufacturers'-spec attitude. I think that's why the likes of Alpina, AMG and Brabus have prospered as they are independant (sort of) but really closely allied to the manufacturers.
In this country I don't think we've got a lot to worry about as long as the parts we fit have some sort of official recognition, such as TUV or BSI approval. Having said that, it's virtually impossible to fiddle about yourself nowadays as electronics are sealed, but I suppose you could change an entire piece of kit or re-write an ECU map.
Actually, come to think of it, it's probably easier to get big performance gains now than it ever was.