i know this has been covered a million time but correct me if im wrong....there isnt many people that can enforce this law is there? for instance the police are powerless, MOT stations are too.....
Not necessarily. They don't have the 'power' to say you can't fit them but they can say that they are potentially too bright or dazzling people and can ask for them to be tested, etc.
The law states that new cars must have Auto-leveling and washers, which you prob won't get on non-xenon std cars.
If you do fit them, make sure you mark out your current lights on say a wall or garage door with some tape, a note the pattern made, say from around 10-15ft away.
then when you fit the new lights ensure they point at the same marks and don't scatter light all over the place otherwise unwanted attention will follow.
Personally, I've yet to see decent set of aftermarlet HIDs, 99% of the ones I've seen on the cars round my way well over ****** in terms of brightness or blueness. Look at some OEM Xenon lights and you'll see its a small round, fine point of light with a clear hint of blue and not some huge mass of blue light blasting out the headlights.
If done right I'm sure it will look good and you'll be fine.... so don't do it on the cheap. Cheap = crap!