Im running a cheap H4 conversion from a local shop (they are DOT; but not sure of the brand; they were $30), and I am running Nighthawk platinum bulbs. HUGE difference from stock; and Ive tried a few different bulbs. Sylvania, eurolites, etc, but they all pail in comparison to the nighthawks. I got my dad a set when they were half off too; and the best thing is the warranty. They only last about a year, but the warranty is good for a year; so you can just get a new set every year, essentially.