Actually John, HIDs aren't illegal on bikes. Look at the new bmws etc, all of which are offered with HIDs.
The law states (for cars) that there must be either automatic lamp levelling, or a manual levelling switch. I assume these bikes must have some form of suto levelling too in order to deal with this part of the law.
I've fitted a number of HID kits to both cars and bikes over the years, and have a pair fitted to my ST4S - both beams (I have the low beam set low so there is no chance of dazling oncoming traffic).
I always use without exception autolamps-online.com
See their sister site
http://www.hid-online.com/hidonline/...motorcycle.htm I've looked at a number of other kits and the weakness is the lamp itself. If these are not made correctly then the light is not focused correctly.
The owner of autolamps used to work for Philips, so really knows his stuff.
I mounted the ignitors onto the outer sides of the trellis frame below the tank using 3mm foam and tiewraps. I also used the relays provided in the kits to ensure the existing wiring is not overstressed.
its worth noting that the 35w HID bulbs give out roughly the same light output as a 100w filament lamp.
its also worth noting that the lamps and ignitors will draw approx 20A startup current. This is only for a very short period of time though, but it does mean you need to ensure you fit a big enough fuse to accomdate this.
Finally, unless you really want the cool bue look, go for the 4100/4300k lamps. These give a greater light penetration range. They still look a little blue, but not as blue as the 6000/6500k ones (the number refers to the colour temperature of the lamps).
Hope that helps.