The new X3 with halogens uses H7 bulbs. And we do carry a conversion kit for an H7 bulb setup that we sell for $99.95. However we haven't tried it an F25 yet so I can't say for certain if it would be a plug and play deal in the stock headlight. Often you need to modify the back covers of the lights to accept these types of kits.
We haven't had much of an issue reliability-wise with these and they have a 1 year warranty. BUT there is a much bigger issue you have to consider when installing these on your vehicle. They aren't legal for highway use. A vehicle that comes from the factory with xenon lights has a completely different reflector design to the headlight and on BMW's they actually level themselves as you drive. Putting a xenon kit in a halogen headlight does enable the driver to see better without question. But without the proper aiming and beam pattern needed for a xenon setup you'll be upsetting oncoming traffic for sure, and getting the attention of law enforcement.