There is more to HID's than a bulb and a ballast. Swapping bulbs and putting in hid bulbs might improve your lumens but your visibilty won't be all that great. Unless you're retrofitting HID projectors or using a special type of HID Reflector (like that found in lexus is300, infiniti, ect) you will have tons of glare. Lighting up the tops of trees, driver's mirrors and eyes, and less light will actually be projected onto the ground.
THIS IS THE TYPE OF LIGHTING YOU WILL GET.
THIS IS THE TYPE OF GLARE ONCOMOING DRIVERS WILL SEE AND FLASH YOU FOR
THIS IS ACTUALLY WHAT YOU WANT
THIS IS THE LEVEL AT WHAT THE LIGHT SHOULD BE AIMED SO THAT YOU DO NOT GLARE AND BLIND OTHERS.
If you plan on simply throwing in a kit then you might as well just install colors bulbs and drive with your highbeams on as throwing a kit onto a reflector housing will not be able to control the light output an HID sytem gives and distribute it uniformly.
Unless you're looking for that riced out (I don't give a crap) look.
All pictures were taken from Hidplanet.com and by no means are any of my cars, retros, ect.
The author of those post has full rights within himself to ask to remove the pictures.