This may help. Take a look at the output as you go up in temp. I stole this info so if someone catches me it's all good. I went with 4300K which I feel is the whitest and the highest outout:

Some background first - "HID light sources also produce a blue-white light that is safer because it is closer to natural daylight. The color temperature of daylight is approximately 4200 K compared to 3200 K for halogens. The increased light output from a 35 watt XENON HID lamp is approximately 80% more light then a 55 watt halogen bulb.

Color Temperature is a measurement in Degrees Kelvin that indicates the hue of a specific type of light source. Many people believe the misconception that color temperature is a rating of the brightness of the bulb or HID kit. This belief is completely false. The reality of the matter is that the higher the color temperature, the less useable light output you will obtain. A perfect example would be a black light. This light has a color temperature of approx 12,000k and has almost no useable light or lumens output. Higher K kits such as 7000k, 7500k, etc. have been manufactured for individuals that are more concerned about the actual color output of their lights as opposed to the actual useable light output they produce."



------------------------------ Approximate
Light Source ----- K Temp --- Lumens (output)
Halogen bulb -----3200k ------ 1500-2000
Sunlight --------- 4700k
D2S bulb -------- 4300k ------- 3200
D2S bulb -------- 6000k ------- 2800
----------------- 8000k HID --- 2500
---------------- 10000k HID --- 2200
---------------- 12000k HID --- 2100


I would like to reiterate that every HID system with projectors (not reflectors) will have a color shift in appearance (visible as you approach an oncoming vehicle or as seen by illuminating your headlights on a white wall) there is that line of blue/purple (and other colors, however minimal) that is generated as the light source bends around the cutoff in your projector headlamp. Now, the whiter the light, the more definition of a blue/purple cutoff you will have. So, if you have 4300k HIDs installed, that cutoff that you and everyone will see, will have a significant amount of blue/purple and a little gold, (pink perhaps too) at the horizon... very defined and eyecatching.

As you go up the kelvin scale, the less variation in color you will see. If you are in blue territory, you will maybe see a dark blue cutoff, but nothing else. Purple HIDs get the same, all purple and no variation.