I would like to upgrade to HID lights in my 2008 Jeep Wrangler. The stock lights aren't bright at all. My question is, since this would be an aftermarket upgrade, what am I looking at here? Is it as simple as swapping in new bulbs? Are there other electronic modifications I would need to make?
Xenon headlights require different electronics to drive them, but they also need different reflectors and also a light leveling system to prevent blinding the drivers of other cars, because the HID lights are so much brighter than traditional lights.
If you look closely at a car with HID lights, with the lights shining on something in front of them, you will see that the lights basically cut off at a neat line along the top, where traditional lights illuminate up much higher.
If you know someone with HID lights, ask them to show you when they start up. The ones in my car move up and down as they adjust to the load in the car, so that a load in the trunk won't cause the lights to shine higher than they're allowed to and blind oncoming traffic.
I had done some research for my old '94 300ZX that I wanted to see if I could retrofit. The kit for them was $3,000 a pair, because of the leveling system and the electronics to drive them.
My solution? I replaced it with a new car that had HID lights. They are totally worth it, they are lovely lights and I find when I'm driving my other car without them I keep thinking "are the lights on?"
Another caveat: Some places are selling "cheap" HID light kits from Japanese models. However, they can't be used in the US or other left-hand-drive places because the left hand lights shine up higher than the right lights, and they can't just be swapped around. The lights for LHD cars are the opposite, where the right light shines higher.
Additional details are available in this related question: KIA Soul Aftermarket Headlights