The pads I received were actually for the SSBC front calipers. When I inquired about this (to SSBC directly), they stated they use OEM pads for the rears, not some "performance" friction material. I will experiment with pads until I find a combination that works well for me but it was disappointing.
SSBC - Braking Rules
Stainless Steel Brakes Corporation (SSBC) is a cutting edge manufacturer of performance disc brake kits and accessories. SSBC has the disc brake conversion and disc brake upgrade kits you need to increase stopping power in your Mustang or Lightning. With various kits offering 4 lug rear disc brakes, big brake upgrades, 5 lug conversions, and drilled and slotted rotors, you can easily outfit your Mustang with the best braking components in the industry at LatemodelRestoration.com.