Hawk HPS pads are excellent upgrades. Just make sure you bed them in with the rotors properly so you have good contact. I don't quite know how effective this would be for only the rear pads, but I've done this procedure twice when replacing all 4 pads, and then only the fronts. By "do not drag" they mean minimizing the time you're stopped with the pads clamped to the disks, and dragging to a stop. Here is the procedure from Hawk themselves:
- After installing new brake pads, make 6 to 10 stops from approximately 30-35 mph applying moderate pressure.
- Make an additional 2 to 3 hard stops from approximately 40 to 45 mph.
- DO NOT DRAG BRAKES!
- Allow 15 minutes for brake system to cool down.
- After step 4 your new pads are ready for use