This was my reply in another similar thread but also seems to apply here:
^If you are going to install HID into the foglight area, you should definitely retrofit HID projectors. If not, you are going to produce major glare. IMO, it is a pretty cool idea but it is an adequate amount of work with no real payoff. Halogen foglights arguably work just as good or better. You will notice that no cars come from the factory with HID foglights.
At one point in time, I started working on retrofitting my fogs (even though it was with halogen projectors). I failed miserably and wasted a nice little chunk of money. I ended up buying Nokya yellow bulbs and I am happy now.
Also if you install yellow HID foglights (which is the way to go or it is completely functionless), your foglights will drown out your headlights completely when they are on.
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Old Car: '03 Toyota Camry LE
New Car: '04 Black ES330 (Aftermarket sound/navigation system installed)

Always got something else in mind...