The first part of this statement is correct, but that's not it folks. In every study I have read on this subject everyone agrees that you also get a slower, better controlled, and more complete burn with a higher octane and this, depending on the individual vehicle, may or may not improve fuel economy and power or in some cases may make it worse.
That's true, so there isn't any single general statement that can be made about octane vs. power, and cars like Corvettes are not the only vehicles that maximize performance based on octane levels.
In a modern turbocharged car it depends on how the vehicle's ECM controls ignition timing, valve timing, and boost vs. knock detection readings, and how sensitive that relationship is. If you run higher octane and the ECM keeps ignition timing advance, and boost set higher due to reduced knock then the engine will make more power. Conversely, if the ECM doesn't detect knock on lower octane fuel and it doesn't retard ignition timing or boost then it can make just as much power on lower octane fuel.
I think with a compression ratio of 10.6 and boost reaching up to 16 lbs our ECM's will be sensitive to knock readings, and will adjust timing and boost accordingly on the fly. It's a very seamless process which can't be detected by the driver but it can affect power and fuel economy, timing and boost maps can be constantly changing. Always worth exploring octane levels IMO.
I know that I can dump 87 octane into my S2000 which normally takes 91 octane. It will run perfectly safe, but performance will decrease as ignition timing will be retarded by the ECM, much like it does with high intake temps and high coolant temps. My old Dodge SRT-4's would behave the same way, very much dependant on how the ECM adjusts performance based on sensor readings.
I hope to toss on an intake in the next few weeks so a bit more octane could work well with leaner air fuel ratios. Just a guess and I'll try to track the engine performance along the way.