Here is some good info to help people decide on what to look for before they buy a HID kit.
Some important information I came from this site and this site
"Colour temperature ('K') vs brightness...It is a common misconception that higher colour temperatures (K’s) produce brighter lights. This is not true. The colour temperature only determines the colour but not the brightness of the HID light. The Colour Temperature is simply a scale represented by the Kelvin Temperature Chart (hence the abbreviation “K” or “K’s”) as decpited above that measures the colour of the light output. Typically, the higher the colour temperature, the closer you get to achieving bluish to purplish light colours."
"The higher the Kelvin, the less light output you get (lumens).
With that said, anything over 6000K is basically a waste.
So, what is the best bulb? IMO the 4300K is the best, as it has the highest light output. The problem, though, is that they have a yellow-ish tinge to them that some people find un-attractive. In that case, 5000-6000k is a better choice for you..... as they have a more blue look to them."
Here is a good chart
Some other good info from this site
And a comparison of Kelvin to lumens;
Standard OEM halogen 55W 9006(HB4) = 1100lm (lumens)
4300k D2S Philips = 3200lm (lumens)
4300k D2R Philips = 2800lm (lumens)
4300k D2S Philips = 2400lm (lumens) actually 5800k
4300k D2R Philips = 2000lm (lumens) actually 5800k
4800k D4S/R (brand) = 3800 (lumens) ** brightest in the market
5800k D4S/R (brand) = 3300 (lumens)
7000k D2S other = 1790lm (lumens) *(other bulb brand)
7000k D2R other = 1390lm (lumens) *(other bulb brand)
8000k D2S other = 1180lm (lumens) *(other bulb brand)
8000k D2R other = 780lm (lumens) *(other bulb brand)
Higher than 8000k, the light output significantly drops off, causing the light to be almost useless.
One should point out that although light output drops off after 8000k, the fact that the light is in the blue-purple spectrum, it still puts a major strain on the eyes of others.
More useful information
And finally, for anyone searching for information on HID's or lighting in general, here are some important terms to know:
(Thanks to HIDPlanet)
Watt- Measure of electrical power (w)
Volt- Measure of electrical charge (v)
Kelvin- Measure of color temperature (K)
Lumen- Measure of light brightness (lu)
Capsule- technically correct term for a HID "bulb".
Candela- Measure of light intensity (cd)
Ampere- Measure of electrical current
Cut-off- A distinctive line of light produced by the shield in a headlight that blocks light above a certain height in order to prevent blinding of other motorists.
Beam Pattern- The pattern of light that is projected onto the ground which includes angle of lateral dispersion, width and depth of illumination.
Capsule- Another term for an HID bulb. Some refer to HID bulbs as gas discharge capsules.
Optics- The lighting control assembly structured around the bulb, which effects the dispersion of light and it's characteristics to a great degree.
HID (High Intensity Discharge)= Gas Discharge
This is the kit that I've used in the past because its very affordable (I bought the 35W, 6000k kit and the lumen rating is 3200lm). For my next HID kit my goal is to find a 55W kit in either 5000k or 6000k temp with the highest lumens for that kit. So spending a little bit more money isnt a big deal.
Here is one kit that interests me. Specs from the site: 55W about 4200lm 6000k temp. this sounds like a better upgrade then the one I'm using in both of my cars.