Superbrightleds.com has 1157 compatible taillights that have a full 180 degree coverage, utilizing the entire refelector. They are extremely efficient and very bright.
This is not an ad for those guys. I have been using the product for a few years now and they work great.
May I also suggest a brake light flasher. Custom Dynamics sells the one I use. It gets attention better than a regular taillight.
Good stuff. May keep you alive, the cagers are blind.
1979 GL1000 Goldwing / 1992 Nighthawk 250 - Baby
2003 DL1000 - Priscilla / 1997 Concours - Ms. Piggy
2002 DL1000 - Fluffy the Torque Monster (Deceased)
2003 DL1000 - Freya, Queen of the Valkyries