Full Tilt Boogie Racing make a two piece rear rotor/bracket that uses the stock rear caliper, but the rotors are 13 inch. Looks pretty nice. Little extra leverage for the rear.
I tried to look into 2-peice rotors, but that idea got poop-canned when it was discovereed that the ATS caliper would contact the center hat on some of the 2-peice setups. My idea was Baer center hats with Corvette 1.25" rings.that's another good one although not sure if anyone has made them work with a 1.25" rotor although i know there was talk of the 13.4" corvette rotor, which is 1.25" thick being nearly identical offset wise to the cobra, so one would just need to re-drill for the ford 5-lug and increase the center hub diameter as the vet uses a slightly smaller one