Not sure I would stick in something with 90 or 100 watts. Not sure about the electrical system but the heat will be significant and damage to the reflector or lens may occur. I just replaced the low beam bulbs in my GL1800. It uses 55 watt H7 bulbs. I looked a the bulbs that say 25% and 30% more light (for almost double the price as well) in the same wattage. Reading the fine print on the packages it says that the normal lights degrade over time and run at 80% of the original brightness. Reading on it says the bulbs are 30% brighter than the stock bulbs at 80%. Net gain about 10% over the regular halogen bulb. I went with the regular bulb and when I replaced one of the two lights I turned on the bike and wow, the new regular was very much brighter than the old regular one that was about 4 years old. I had not realized that the bulbs degrade over time and went ahead and replaced the other bulb as well. The H7 Halogen can be bought at Walmart, Autozone, etc. The x500 uses the H4, you may be able to get them there as well. That way you can read all the fine print on the package backs. If you want a lot brighter light and stay within the stock wattage you might want to see if they make an HID setup for the x500.
