You probably won't feen much if any difference.
Octane is basically a detonation rating.
In a G2, as long as you run the recommended 91 Octane and up, you're fine. This just means that as long as you use gasoline with an octane rating of at least 91, you will be able to avoid pre-ignition, and thus harmful knocking. We don't need anything higher than that.
Side note: You will probably not experience knocking if you used a lower octane gas because our engines are equipped with knock sensors that retard timing if it senses knocking. You will, however, lose in performance.