HID FAQ and answers:

1. Is 8000K brighter than 6000K?

No. The Kelvin scale is a measure of colour temperature, not intensity or amount of light. HID setups that produce maximum light output are around 4100-4300K colour temperature, and the higher you go, the less light output. A 12000K HID kit will be dimmer than your stock halogen lights. 4100-4300K kits will have the colour of all the HID lights you see on cars that come equipped with them (like most BMWs, Mercedes-Benz', and other luxury vehicles). The colour is very white, while light output becomes progressively bluer as colour temperature rises; 6000K is white/blue, 8000K is very blue, and above that you go towards purple.

Here are some links for this topic:
What is colour temperature: http://www.hid-online.com/hidonline/...colourtemp.htm
More on that: http://www.hidkits.com/tab_faqs_color.htm
General HID info (scroll to bottom for stuff on brightness): http://faqlight.carpassion.info/hl-general.htm

2. What HID kit should I buy? What is a good price?

Aftermarket HID is sold by a large number of companies, although less so recently because of NHTSA regulations. However, to ensure the highest quality, make sure you buy HID that is made by an OEM HID manufacturer. OEM HID kits are the same products fitted to many vehicles (usually luxury) by manufacturers before they are sold as new vehicles. See this link: http://faqlight.carpassion.info/car-oem-hid.htm. Notice that almost all ballasts and bulbs used by car manufacturers are Bosch, Osram, Philips, or Hella. Bosch and Osram are not as readily available for retail, but Philips and Hella are. Kits that are not made by these companies are most likely not of the highest quality, although some aftermarket manufacturers such as Brightstar and McCullogh have been recognized as high quality products as well. Philips/Hella kits are generally considered the best.

As far as price is concerned, the cheapest I've seen for a quality kit like Philips/Hella is about $275 on ebay. Most online retailers sell them for $450+. Anything below $400 is a pretty good deal IMO. Here is a site that has a good rep and sells all-Philips kits: www.xenonfactory.com. Google "philips HID" for more, or search this forum.

3. Can I put HID into my stock halogen reflector lighting assembly?

Yes. But it is strongly recommended that you do not. Although it may not seem so, directing the light produced by a headlight bulb to the right places requires a good deal of precision. Reflector assemblies on cars that come equipped with halogen bulbs are made to direct the light produced by halogen bulbs correctly. Replacing those bulbs with HID bulbs that produce three times the light yields a terrible beam pattern. You will have light going all over the place, most importantly into the eyes of drivers of oncoming vehicles. Even if you can tolerate such a beam pattern, your lights would be a safety hazard on the road. Many people try to solve this problem by lowering their lights. However, to reduce glare to acceptable levels, you would have to lower HID lights in halogen reflectors so much that you would not have much of a useable light increase over your stock setup.

http://faqlight.carpassion.info/hl-hid-kits.htm
http://faqlight.carpassion.info/hl-reflectors.htm