OEM Tune on the C6 Z06 includes tables for both 91 and 93 Octane fuel. My car is tuned for 93 Octane and I am careful about what fuel I put in the car. I used 100 Octane Sunoco at a track day and could not tell any performance difference from 93 Citgo.
You have to have the entire tank with 100 octane (no mixing) and to run the car on 100 before the track day, preferably consume a tank of 100 gas before. The auto-adjustment of ECM for using higher octane is very slow.
Another option would be to reset the ECM using LS7edit or similar so it would start with aggressive timing.
More than this, if you want to take full advantage of 100 octane gas you must have the ECM re-flashed with a specific tune/program.
Especially when using Sunoco gas which has 15% ethanol.
After that you will be able to tell the difference at the track.