"why would you use 8k when that gives you stock output of a halogen bulb?"
Dude what the hell are you talking about?
8000K is the color temperature. Stock halogens color temperature is between 2300K all the way up to 3500K and the light out is about 800-1200 lumens.
My HID's are 8000K (Blue/White) and about 3000 lumens (Probably more like 3200). So they are much more brighter and intense then Halogens and consume less power (35watts compared to 55+).
What I would like is to get a lower color temp bulb like lets say 5500K so the light emited will be more white.
The spectrum goes red, orange, yellow, white, blue, purple.