It seems like retrofitting LEDs into the stock projector is just too difficult. Try one of the 20mm housings from easy2led. You can use a XM-L, triple XP-G or for a narrower beam a triple XP-E. Don't try to max the power because the heat dissipation will not keep up if you are stuck in traffic. If you only use them when moving then even a small housing should allow you to put out some major light.
http://www.easy2led.com/images/housing_small.jpg