the wrx rotors are 20% bigger and have better cooling than the RS, but have the same front caliper but need a different caliper bracket....same with the rears.

edit: its nothing too crazy, but I needed new rotors and pads, and to upgrade was only like an extra 60 bucks so I said fuck it why not.......my next upgrade for the breaking system is this though:

Legacy GT Rear Brake Upgrade
Upgrade your rear brakes to those found on the Legacy GT Turbo model. Kit includes two 11.4" vented rotors, two one-pot calipers with brackets, and one set of pads

Subaru 4-Pot Front Brake Kit