Ok, so I got stoptech's from riverside infiniti. I pulled of my rear right OEM rotor and noticed there was a size difference in the stock to the Stoptech.
The rear face of the stoptech and oem are the same in the backside of the rotor. However, the front, or facing outside (towards you) is about 1/2 inches smaller than the OEM. Is this normal?? I called riverside and they say the stock number is what is needed for my car. However, the size of it is def smaller.

IS THIS NORMAL? please help

 

huh? How about a picture

 

Sounds like the rotor offsets are diff. Which is no biggie as long as the caliper mounts up fine and the E-brake still functions.

 

did you buy all four? are you sure you are putting the rear discs onto the rear of the vehicle?