Running the 91octCAI tune in my Charger SRT8, with 3% fuel increase across the board. What gains would be had by adding more fuel (let's say 5-10%) across the board?

Running the 91octCAI tune for my Charger SRT8. Had the 17 version, and the car shifted with hesitation, then I checked and noticed that my car registered a P0300 code: Engine Misfire Detected.

I ended-up installing version 18 and all is well, but what would have caused the engine misfire? No ...