All you need is HID bulbs + ballasts. There are many different palces you can buy hid upgrade from... Price can begin like from $40 to $500. Stock hid lights or and Phillips HID would costa lot, but they are a good quality ones. I bought mine from vvme.com for like $100 shipped, now i tihnk it is close to $70 shipped, i like them a lot.
I dont know about others (you can search) I bought mine from vvme.com
You need H7 bulbs and you choose what color you want... I think 6000K is the most popular, and 8000K.
If you dont want to go the HID route, I just put in the PIAA Xtreme white bulbs last week and I really like them (as compared to stock halogens). Nice white beam with a slight hint of blue...but not ricer blue!!!
Looks very tasteful and lights the road much better than stock bulbs.
I am planning to get VVME which ones would u recommend the 6000 or 8000K i kinda like the 8000 and how hard is it to install or set up and the kit is like $40 so i dunno if that includes it all
__________________
2005 Audi A4 1.8T Ultra Sport Black/Black
Forge 004-VVME 1000K HID-APR Stage 1+ Chip-
You need to buy a Conversion Kit which includes 2 bulbs and 2 ballasts.
It is up to you which one you like 6k or 8k... They say that more K's you go, lees light output you get, but still i think the biggest one 12000K is brighter then the halogen. My buddy got 8000K on headlights and 8000K on fog lights, that is Bright!!! Looks like brighter thham my 6000K, but his looks more blueish on a road.
I dont know wher you from, but if i'm not wrong, in some States 8000K is Illegal.