I used to dabble with HID back in my younger days of hot hatches
Of course it was all the rage, but in practice not too great!
The law regards washers and self levelling only applies to new vehicles, however it is technically against the law to use HID bulbs in halogen reflectors, if they couldn't do you specifically they can do you for improper maintenance of your headlamps.
This is the same story for 100watt bulbs although I've been using them for a long time and since upgrading the wiring in the pokey 200 system I'm now getting very good vision compared to what was a dim candle before.
As such, you'll be good to go in your Audi if you wanted. On that basis why not upgrade your low beam h7s because you won't have a problem.
The reason that HIDs are a problem is that the beam pattern is not controlled properly in the halogen reflector.
If you have projector lenses then by all means upgrade to HID you won't have trouble, but when fitting hid to halogen reflectors you simply get a wash of light all over the show, and actually have a worse useful light output than you did before.
All that light that is dazzling people should actually be being focused and directed onto the road ahead so it's wasteful and dazzling.
The best bet is to either get a set of Osram Nightbreaker as they're considered the best lamps off the shelf or fit 100w halogens and enjoy whiter and more piercing light.
The more output you can get down onto the Tarmac and trees in front of you the better your vision will be and halogens do it right, keeping it focused so even if you're burning 200w on dip (had 200s in a Suzuki a while back but they just ran too hot and get blowing) as long as it's focused the only thing people might notice is how white your lamps are, but they still won't get dazzled.
Cheers
