I wrote engine models using Simulink that ended up in Delphi controllers... arghx7 has/is working in industry
What he's trying to say is that if you increase the octane you will see more ignition advance which may lead to more power... IF there isn't ignition advance limits.
What he's not said, which I think is important is that with the increased octane you will not have your knock control strategy retarding the ignition advance... which means that the ECU won't reduce the power output... which conversely means that you'll be making more power.
For the poster that was saying that you won't be able to ignite higher octane fuel... that's a fallacy. You could run 100 octane in your BRZ/FRS and you're not going to have the thing misfire. This isn't like trying to start an engine running on E98 when it's 40 degrees outside.
If you study the combustion process in the cylinder a bit more you'll see that it's the temperature and pressure the end gas sees near the cylinder wall is what the addition octane is there for. Once the flame kernel reaches the end gas it will be ignited... no problem there. For fun think about the in cylinder temperature and pressure that the end gas sees... degree by degree. It'll start making more sense.