Light scatter FTL.
If you do go HID, stay below 5000k.
Factory HID is 4300k, because that's the closest to sunlight.
HID's will color shift and turn a touch more blue in the color spectrum... 4300 will shift into 5000, basically.
The higher the k, the less light and visibility you get... The more blue you get, the harder it is on your eyes, and the worse it will be for anyone else on the road, especially since blue refracts more.
When I had the H1 projectors in my truck, I bought a 5000k HID kit, and in less than 30 hours they shifted to be around 6000k.
Those cheap ebay bulbs WILL color shift a lot faster than OEM stuff... OEM stuff does it, but not usually before 80 - 100 hours, at least.
HID's don't generally work the greatest in a halogen housing, and a 2 headlamp system is one of the worst for it.
The energy arc, doesn't line up quite right with where the filament from the halogens is supposed to go... They can get damned close sometimes, but they still can't match it.
Projectors are the best thing to do when going HID.
