Oops...you made an error. The "improvement" from Sylvania Silver Stars is an optical illusion. Their actual, objective performance is very poor. If you are buying sealed beams, you are much better off for less money with GE Night Hawk H6024NH, about $18 apiece, as linked in many threads on this subject on this board.
Ask questions and get good answers here before spending money. The guy in the store just wants you to buy the most expensive thing he has, whether it's crap or not.