LS6 Tommy said:
Most of you guys know I'm not one to flame anyone, so don't take this as an attempt to insult anyone that has HID lighting. There's LOTS of misinformation floating around on car websites about converting to HID.
H4 bulbs are not HID. They're incandescent. Keeping that in mind, using a "plug & play" HID bulb in an H4 reflector is a sure way to spend good money to put less light on the road & blind people coming the other way. HID bulbs use an electric arc to make light. Incandescents use a filament. The HID arc is perpendicular to the H4 bulb filament. There's no possible way to use the reflector for an H4 bulb with an HID bulb & get any type of usable beam pattern. The HIDs are designed for projector lenses, period. Another thing most don't mention is that you will almost definitely lose either your low beams or your high beams unless you spend some pretty good money.
My suggestion would be to get in touch with Daniel Stern. He can hook you up with a relay kit, REALLY good H4 reflectors & bulbs to optimize your headlights without spending anywhere near as much as you would for a true high/low beam HID system with decent electronics/ballasts. At the very least, there's good info there to read.
North America's Premier Automotive Lighting Consultancy and Supply
www.danielsternlighting.com
Now, if you're dead set on getting an HID conversion kit, get relays like TTLSX418 mentioned & don't be talked into getting anything without a separate, quality ballast.
Tommy
Ok there are a number of things that are wrong in this response so I'm going to pick this a-part and shed some light on the subject.
1.) First there IS an H4 HID bulb and there IS an H4 incandescent bulb. The HID bulb just has the same mounting base as the incandescent which allows the HID part to be retrofitted AND the HID bulb (or the correct HID bulb) has the proper reflectors built onto the bulb base.
2.) ALL HID bulb arcs are perpendicular to their bulb, even the ones that come stock on vehicles from the factory. The electric arc is ignited by the ballast and heats the noble gases (xenon, krypton, and argon) that are in different concentrations coherent to the temperature you purchase when you order the lights. That is why the lights look like they "pop" when they turn on and get brighter as they warm up, because they are in fact warming up all the gases. (4300, 6k, 8k, 10k, 12k, 15k, 30k,)
3.) HID bulbs ARE NOT designed strictly for projector housings. There are plenty of vehicles that come from the factory with normal headlights, having no projectors in them, that utilize the HID bulb. For example... first gen G35 coupe/sedan, first gen prius (that have the option), second gen escalades.... the list goes on. It is all about aiming the reflector. The bulbs are better used in projectors lenses but are not specifically for them.
4.) You WILL NOT lose your either your low or high beams if you purchase an HID kit. They have what is called single beam HID kits and Bi-xenon kits which have a magnetic actuator that will pull the actual bulb back into the position the high beam would take. I know this because I have some on my daily, and they work great. Again that is called BI-XENON. Google it.
Don't be scared of HID kits, they put out GREAT LIGHT but using them safely and aiming them properly is KEY to being friendly to everyone on the road.
I read that site you posted and he has a lot of great points, but you don't have to go through retrofitting a projector lense to get great light output from one of these kits. I know he argues against every single point that I have made, but I am basing my knowledge/experience off of trial and error not reading books or cruising ebay for cheap knock-offs.
Don't be afraid, these kits will work safely and effectively if you take the time to set them up right.
No disrespect to LS6Tommy, but that's just the plain truth. If you have any more questions let me know.