Got 'em! I just picked up a set of Brembo 4 piston calipers to use with Jamie's Cobra brake upgrade. They are from a 2000 Mustang Cobra "R". The calipers bolt right on in place of the Cobra PBR calipers, and use the 13" Cobra rotors.
The stopping power should be adequate , and they just look friggin' cool. I may need to tape my eyeballs in before stomping the brakes. Starting out, I'll stick with cheapo replacement rotors ($16 RockAuto) , but would really like a 2-piece similar to the Baer Eradispeed setup, for light weight (okay, okay, I'll admit it: and the bling).
-Now all I need are those hubs and adapters... j/k Jamie!