I was always tired of the yellow lights that didnt show crap. well its a long story with that, but I first converted to the 165mm free-form housings made by hella purchased from
www.rallylights.com (~100). I had H4 100-watt lamps in there and that did do a nice job. After tons of research I purchased a Kaixen HID kit from m_specs off of ebay (buddy of mine purchased from him so thats why I went with him) . I did not want to lose my High-beam ability so I purchased the H4 high/low kit which is a good deal more ($395 shipped). It uses a movable shield to reflect the light differently. If you do not care about the high beam then I think the kit is like 320ish maybe. This is indeed more expensive than other HID kits you will find all over the net, but many kits are garbage while this one really does feel of high quality.
I could go on and on since I've turned over just about every rock to find info about all that there is to HID lighting and this is what I came up with for our car. One guy did actually fit a projector into our housings but I could not get enough info about it to feel confident in going that route (lot of cutting and hacking with no idea if the headlight could go down anymore). The only real way to make this work the best it can is with a shield, otherwise glare would most likely have been crazy and dangerous. If you are deciding to go this way then feel free to ask me any questions. It's expensive and it was a stretch to do this but I'm always trying to be a little different than the other guy.
BTW, adjusting the lights is done by screwing in/out the two star pattern screws at the top and side of the headlamp. You can do this without taking anything part. Pop the headlamps up and turn off the lights (if you dont want to see spots lol) and adjust them. There are a lot of online writeups on where and how the beams should be aimed so take a look.
-Brian