How much more power are you looking for? Another option may be to reduce your existing electric load. I have a 2000 XC300 with the 35W 2k2 ignition and I found that you can run the stock headlight just fine if you change the tail / brake light to an LED style. LEDs use much less power than the traditional incandescent bulb. With the incandescent tail light/ brake light bulb, the headlight would pretty much go OFF every time I hit the brakes. The inrush current of tungsten incandescent bulbs is roughly 10x normal operating current until the filiment gets hot. It would take a few seconds for all of the lights to come back on every time I hit the brakes.