If you want brighter, get etiher Osram Night Breakers or Philips Xtreme Power bulbs and put them in the stock housings and make sure the stock lenses are cleaned and not hazy or anything. Then make sure the stockers are aimed right.
Only other way to get brighter is to do a full HID retrofit (not putting HID bulbs in the stock housings, a full on retrofit). And you really don't need brighter with the right halogen. Parts store sylvanias and the silverstars are not really that great.
2000 Mustang GT Steeda #0048
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.