I've not had luck with the Sylvania Silverstars, and I don't know why they get such good press. Granted, the light they provide is AWESOME, very bright, very clean... but I only got 2 months out of one, and 6 months out of the other! And this was in my '95 Jeep Cherokee! I can't imagine how it would handle the vibes of a bike. Any bulb that's that 'fragile' is more problem than solution, especially at the price they're charging!
I went back to standard Sylvania halogens, and they're still going strong, 2 years later. I'll stick with H3, thanks.