The '05 rotor size are the following:
front: 12.8 x 1.26 / 325 x 32;
rear: 12.0 x 1 / 305 x 26
Z51 Performance Suspension:
front: 13.4 x 1.26 / 340 x 32
rear: 13.0 x 1 / 330 x 26
The '06 Zo6 rotor size's are the following:
Front 14-inch (355-mm) cross-drilled front disc brakes with six-piston calipers
Rear 13.4-inch (340-mm) cross-drilled rear rotors with four-piston calipers
Complementing the suspension system and large rolling stock is an equally capable four-wheel disc brake system, consisting of 14-inch (355-mm) vented and cross-drilled front rotors and 13.4-inch (340-mm) vented and cross-drilled rear rotors. For comparison, the ’05 Corvette has 12.8-inch (325-mm) front and 12-inch (305-mm) rear rotors, while the ’05 Corvette with the Z51 has 13.4-inch (340-mm) and 13-inch (330-mm) rotors.
Here are some bits from CorvetteMuseum.com
So far I have found a Stoptech rotor that will have a 5x114.3 Bolt Pattern with the dimensions of 355mm x 32mm Rotor. Prices start at $255 for a blank rotor minus the hat.
http://www.stoptech.com/products/rotors.shtml