Darkfox, I'd like to contradict your statement... at least if your in an area with lots of fog or snow... I have the 520 fog's in mine and the 80 XT fog's right next to it (which are about twice as bright). Aimed exactly the same, in a snowstorm or in dense, dark fog, the yellowish 520's will light up the road MUCH more then the clear 80 XT's will. The yellow light finds its way through the white snow and fog to the road. The clear just bounces off and reflects back at you. I'm not sure if thats because of the color (but I'm pretty sure it is) but I'll be converting one set to 520 MSR (which is a clear fog) as soon as they are available (end of this month supposedly) so I'll know for sure whether clear or yellow is better in fog, independant of wattage differences. For everyday driving, I prefer the clear, but for fog and snow, nothing beats the yellow.