I tried the Silverstar.
The Silverstars sold in the US are blue coated and that reduces the life of them. The Osram silverstar is the Euro version, w/o the coating and is brighter. You won't find it hanging on a hook at Advance Auto, that is the Sylvania Silverstar (Osram?) H4/9003. (H4=9003)
In addition, the Philips VisionPlus is similar to the Euro Osram.
You want one of these for max output @ stock wattage.
Sylvania Silverstar is an improvement to my OEM bulb.
I was not happy to discover the life expectancy of this Silverstar. Euro version lasts longer due to US ver. "blue coating- marketing gimmick to make it whiter.
W/ my luck it will go out on the edge of a decreasing radius cliff-hanger like "Toonces the Cat".
Good discussion:
http://autopia.org/forum/archive/index.php/t-44340.html