
1. make sure you have rear brake pads AND PAD RETAINER CLIPS for a 2002 WRX.
I had the pads but not the clips (thanks Zak)
2. make sure you have 2 bolts of the correct size to thread into the rotor if it is frozen to the hub.
I didn't, but I'm sure you can guess who did...
3. make sure you have a large diameter, very sharp drill bit to remove the dust shields.
I had a sharp drill bit and Zak had a large drill bit, between them I got the job done.