I'm running Summit's H4 conversion set (
http://www.summitracing.com/int/part...9250/overview/) - they claim they're 60% brighter than sealed beams and still street legal. I can't verify that, but I'm happy with them.
I have third, centre mounted brake lamp on my car. It's a 9" long strip of LEDs (
9 in. Red LED Light Strip | Princess Auto) mounted to the bottom of my full width roll bar. It lights up pretty well and is much higher than the tail lamps, so more visible to vehicles behind.
I also have a pair of red reflectors, roughly 4" x 1" under the body that help trailing vehicles - as long as they have their headlights on!
Not done yet, but I'm going to pull the lenses off the tail lights and put foil tape on the black lamp bases. That should increase the amount of light going back through the lenses and improve visibility.