You pretty much nailed it except for the part about a stock car making more power w higher octane, but you were close. The more timing you run the more power you make and the more timing you run a higher octane is required so there won't be any detonation. Say you have a car that is "recommended" of 87 octane and you put 93 in it's still going to have the same power because the timing wasn't advanced. What is the recommended octane for the coyote anyway? Say it's 91 and a company runs it on 87 and retards the timing for a base pull, they could really fudge a test.
The Coyote has a dual power rating. 402 for 87 octane and 412 (11-12) for 93. The computer continually advances timing within programmed limits. This means a tuner can easily fudge numbers by changing gas.