I installed after-market HID 5000K on my 3 BMW motorcycles over the past 4 years, and rode cross country several times. Never had an issue with LEOs in all the states, even when I got pulled over for going 92 in an 80 zone in West Texas.
All HID vendors have a disclaimer "For off-road use only" but you can read between the lines... they are just covering their ass.
HID will give you almost 3 times the amount of light you get from halogen. So... HID away and see the light!

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Gilles & Kathy
Quattro... because I like her on all 4
Unofficial SoCal Crew member 
05 Dark Graphite BMW K1200LT
05 Audi A4 3.0 (For sale)
00 Audi A6 2.7T (Spare bike)
03 Saab Convertible (Other spare bike)