Originally Posted by BarManBean
I don't really know why people say this...? The fogs generally suck anyways, so why not replace them? Granted, they still won't be good foglights if you go HID, but they would be extra light output for sure.
There are fundamental reasons for fog lights not being brighter than the sun.
Output from an HID source will dump MUCH more light into a projector ABSOLUTELY not designed for it. In projector headlights, this isn't a HUGE issue. The design of a projector can put light where it needs to go nearly independent of the output source. Headlights, unlike fog lights, are designed to throw that light a great distance. Increasing lumen output in a headlight just throws more light in approximately the same locations.
But in a fog light, especially a projector fog, that added output does very little other than increase scatter against fog and snow. What you end up with, is getting blinded.
OK, so don't use your fog lights in the fog, right?
Well that's not such a good idea either. Fog lights have a wide spread, very close to the front of the car. This is exactly what you want in a fog light. It's exactly what you DON'T want in a driving light. So now you have enormous light saturation, very close to the front of the car, and for a relatively short distance.
From a night-driving performance standpoint, this is the trifecta of shitty light design. All it serves to do, is draw your eyes off the distance and to the very front of the car. Exactly what you don't want to do when you are trying to see.
If you want driving lights, get driving lights. Don't put HID's in your fog lights. The only purpose it will serve, is looking "cool" in parking lots.