There was no optional brake package on a '06 Z06.
Here’s the '07 brakes: http://www.chevrolet.com/pop/corvette/2007/z06_brakes_en.jsp same as '06. And they suck. I know, plenty of my friends have 'em. The guy I got my car from sold it to buy an '06 and he had those brakes, hated them, and now runs Stoptechs.
FWIW I can get all 4 calipers, rotors, factory pads, and the brackets to run C6 Z06 brakes on my car for ~1600. That’s far less than any other big brake answer out there. But it’s just not worth it. The pads cup, and having six per caliper front are super expensive and a massive PITA to change @ the track. The rotors were also miss-engineered (or GM just got really really cheap). Instead of true left and right hand rotors there is only one type. So on one side of the car the rotors turn the wrong way for the cooling veins to be effective.
I though you had one, why don’t you go look?
-TJ