Let's clear up what your doing first.
We have 7 different rear rotors for Subaru's, all O.E dimensions.
Do you currently have the standard solid or vented rears now?
These are the standard rears I have listed for your car.
The upgrades would be,
All rears except for the DBA 655 will fit under STD 16" wheels.
The DBA 644 and DBA 649 are for 15" wheels.
Let mw know if you have any more concerns