Well, MrBeal, my suggestion would be take a bulb out and stop by the local Autozone or similar auto parts store. Might be able to get a bulb that is a replacement but halogen or some similar higher output that will give you the brightness you desire.
If that works, add to this post so others might be able to do the same thing. Good Luck!
If that works, add to this post so others might be able to do the same thing. Good Luck!