use the ballast that is matched to the coil. here is an excellent Q/A on what the ballast is for. kinda long though.
http://www.imperialclub.com/Repair/Electrical/coil.htm

the bottom line is if you match the componets together the way they are recommended, they will last longer. the numbers i posted are probably wrong as i was going from memory but the amount of CURRENT reduction is minimal between my post and Sinitro's. will it work without a ballast? yes, but for how long?