I thougth the bulbs in the ST were standard H4's. Or am I wrong.

anyway you can get those from many places, think halfords do them for 5.49 each. Or you can go for some mega bright (slightly illegal

) race lights, 160W output. I got mine from Grand Prix Racewear (as i get discount there) they are normally 35 quid each, they are made by PIAA and are very bright white lights.
Dont know if that was any help.