I got a replacement set of bulbs from www.dealextreme.com They are rated 50/100w. I gave one to my neighbor. We have been running them all year and no issues to date.
But I would like a 7" bucket to replace my 5"

 

My buddy with a DYNA changed to H4 PIAA - just be careful - I have a post here that when he changed the bulb, he overtightened the chrome ring - not allowing for enough heat expansion and his lens cracked - do not overtighten no matter what bulb you purchase. (DYNA headlight = $100.00 - guessing the Sporty is close to that.