You can have HID in any light, low-high-fogs.
The only problem with HID in fogs is that we have the auto turn on thing when you close the door and you had the lights on before, Iīve been told that is not good for HID (turn on and off quickly-frequently), so I decided to uninstall my fogs as I was having problems with them. (want to ask the dealer if they can turn off that feature as I they looked awesome)
The low lights look great and highly recommended, if you want also high beams, you can do it too, I didnīt do it as when having HID in low ones, you donīt use them that much, but it's up to you!

I now have a question for the forum:
I am installing my HID's again as I got them replaced, does anybody know which is the positive and which the negative to install bulbs? (I can't remember)
I searched on the forum and found:
DFWSBR said: 2 wire side = - and 1 wire side = +
but then NJSPEED69 said: -THE SIDE WITH TWO WIRES IS THE POSITIVE.
So that is confusing and one of them should be wrong.
All of you who have HID installed and have had no problems so far, which is the right polarity?
Thank you!