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.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.
I am not saying that mixing is bad. Any octane increase is good. :thumbsup:I have been mixing 4 gallons of 100 octane with every fillup to get an octane rating of 93-94 since I picked up my car in September of 2005. I have been told those running on 91 octane will not develop full Horsepower even thought the car will run.
I also have a Diablo Tune which leans out the fuel a bit so I was told to stick to the mixing. I also understand that running above 93 will do no harm but will provide no additional gain.
I'm not an expert on this and am making no personally guaranteed claim but I do lots of research and listen to guys who have more racing experience than I do.