the bulb is just an H3 bulb for both high and low beams.
I personally use This in the 35 watt version. I heard the 55 would get too hot for our little housings. HID's are a night and day difference over stock!
I have both high and low beam 55w 6k HID's from ddmtuning.com, I have had them in for 2 years no issues. Firebolts use a 55w h3 in a regular halogen bulb, you can get the bulb at any autopart store if you dont want hids.