The car is designed to run on 87 octane fuel, according to the manual. I don't think it's wise to run a higher octane unless you tune for it.

 

The heating values of both regular and super are the same.
The difference between the fuels is that the onset of the end gas from slow burn (about 500 ft/sec) to knock burn (about 2,000 ft/sec) is moved to a higher temperature and pressure. Since the higher octane fuel further delays this end gas move to the explosive burn rate, it burns more smoothly when pushed to the piston pressure limits.
Ford uses adaptive timing, which detects knock and adjusts accordingly. The regular burns OK, but the timing is set for maximum efficiency for the fuel, which is a very light pre-knock condition. When you give it a fuel that delays the onset of knock, the timing will advance a little bit more, giving you a slight improvement in power and efficiency. Although not enough to offset the 20 cent increase in the fuel at these prices, I like the smoother running engine. And yes, I don't think the engine takes full advantage of the increased octane rating, but it still might be an interesting experiment if someone wants to try a couple of tanks of premium to see if the drone is reduced.

 

Put a right side GT takeoff on tonight. Goodbye drone!!!!

 

Nice! I really enjoyed having the GT take-off muffler on my car.... it's really a nice improvement over stock. But, later decided to go with duals.