I'm sorry but that's wrong. First, there is no "white" in the spectrum. There is, however, blue and that does tend to scatter more than red. HID's are perceived as being more blue than halogen's and their color temperature is generally somewhat higher (and thus bluer) than halogen, but not by that much. Halogen tends to have a color temp around 3200K and OEM HID is around 4200K (which is the average color temp of sunlight in the middle of a summer day on Earth, exactly what human eye is adapted to best see). However, the common perception that HID's are "blue" does not come from their 4200K color temp, but rather artifacts produced by the projector mechanism such that the edges of the light beam get a bluish, even purplish sparkle to them. That phenonmenon is the reason people think HIDs are "blue" and all the ricer madness to get higher color temp bulbs comes from that side-effect of HID projectors (not HID reflectors, just projector systems).

I bet that Hella does not have a high-beam HID lamp at all, the reason is that HIDs take a while to warm-up and achieve full brightness maybe even 20-30 seconds depending on the mechanism (although there are apparently some military-grade short-arc systems that do have a kind of instant ignition, these aren't used in either military or commercial headlights, only in spotlight systems, so far). While the common use of high-beams is to need the extra brightness RIGHT NOW, not 30 seconds down the road...

The common commercial implementation of HID high-beams is to shift the shield in the projector to open up the vertical aperature in the projector by a few degrees (or at least shift it upwards by a few degrees, depending on the implementation). So that there is no ignition required, you are just changing the beam pattern of the currently ignited bulb. These are usually called bi-xenon systems.

From what I have been able to learn, going with the Hella 90mm system buys a nice heavy-duty projector with all of the appropriate pieces made "to last." But, if you go with an OEM system (like from a BMW or Audi or Lexus) then you often get a projector that works just as good, if not better, but the surrounding hardware is optimized for the specific car that it was designed to go into and as such may have lower design tolerances because the rest of the headlight assembly is expected to compensate. So, if you go with OEM headlights you may find that you have to custom build other parts like the shroud or mounting gear in order to make it work reliably. But the benefit is that you can get smaller lights and better performing lights than the Hella commercial parts.

For what it is worth, I'm looking for a small bi-xenon setup myself. Today I saw a bunch of 350Zs (driving by a dealer) and noticed that they have teeny-tiny projectors, probably less than 50mm, but I haven't been able to tell if it is bi-xenon. Apparently the bi-xenon's off the previous design bwm 740 series are highly prized for looking good and for being relatively small, althought I'm sure they don't come anywhere near the lens size of the 350z's.

Along with hidforum.com which is primarily interested in retrofiting cards, here is a good forum dealing with HIDs, they can get real technical - often far beyond hidforum.com's level and car headlights is not their focus, rather more into handheld spots and floods:

http://www.candlepowerforums.com/ubb...at=&Board=UBB7

they also have other forums for other types of lights, including halogen and LEDs.