You can get brighter lamp for your headlights, but there is a Federal legal maximum wattage. I think it is 55 or 65 watts.
Although the plastic discolors and makes for poor lighting. Polishing is a short term fix, and from what I have seen needs to be done a couple of times a year. Another cause is undersize wiring to the headlights. There are kits to use the existing wiring solely to turn relays on or off, and the relays provide power to the lights from the battery with bigger wires. I have wired the headlights in my Samurai with relays, although not a kit.
