Cross drills may be noisy; the Baer Eradispeed +1 rears are. Zinc or cad-washed rotors stay nice looking longer.
Baer, Brembo, Powerslot, others make choices (drilled, slotted, both) for Cobra F/R rotor upgrades. Ultimately nice if can upgrade to vented rears as well as the vented Cobra fronts. Doing front brake upgrade more important than rear.

http://www.musclemotors.com/index.asp?PageAction=VIEWCATS&Category=5
http://www.allfordmustangs.com/forums/showthread.php?t=53089

Get a rotor that has both. That is what I have (Brembo) and I love them.