I just switched my yellow bulbs for Bimmian Xenesis Xenon-match bulbs. I feel like the output is over all the same. The yellow was definately eliminated. So I would definately switch to Xenon-match rather than stock yellow. I have a 6000k HID foglight kit on the way from Dave @ Custom Angel Eyes/ AngeliBright. I bought the Xenon-match bulbs because I didnt want to spend on an HID foglight kit. But in the end, xenon match is just not enough, spend $100 more for the real thing.

If you decide on sticking with xenon match, my set might be up for sale when i get the HID kit. But i think the HID kit is a better investment for you. (avoid the mistake i did and buy it from the start!)

As for the size, it varies. Check your owners manual.. my 2002 fog bulbs are H3.

Here is a pic with the xenon match fog bulbs (and my new Custom Angel Eye headlights! ):

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