Higher octane has higher resistance to detination. Meaning more cylinder pressure ( boost , static compression , more timming etc.)

Example:
Nothing is set in stone , but you could increase your total timming when running higher octane, which will increase HP.
On a 4 cylinder , I use 400 whp as a safe limit of pump (93 oct) gas, many have made more power but 93 is a little unstable with that kind of cylinder pressure.At that point 100 or higher is a good choice.
Every tuner will have what they feel safe with HP v Octane.

Hope this helps.