Ok, I suppose you can try that with the fogs. But even with yellow output the extra intensity of HIDs could be too much for the simple reflectors in the fogs, you may still get a lot of glare. There also aren't too many HID setups that will fit in there due to the minimal clearance.
Personally for the stock fogs I'd stick with halogen bulbs, you can go with yellow ones like Narva Golds. If you want more light than the stock fogs can produce with halogens, and/or you're really after a driving pattern vs. fog, adding a set of auxiliary lights may be a better idea.