A tune from a reputable outfit (like Black Bear) is one of the best performance add-ons you can do for your truck. Plus you’ll get better fuel milage—if you can keep your foot out of it......
93 octane won’t hurt the motor at all.
I ran mid-grade in my GMT 400 TBI 5.7 for 275k miles, and currently in all 4 of my Vortecs ( a 305 and three 350’s) for years. They go up the pass further before downshifting and average about a mile to the gallon better. Keep in mind my trucks operate at altitudes 5k to 11k ft. Can’t speak for the downstream trucks.....

 

https://www.fueleconomy.gov/feg/octane.shtml

"

Why do some manufacturers require or recommend the use of higher octane gasoline?

Higher octane fuels are often required or recommended for engines that use a higher compression ratio and/or use supercharging or turbocharging to force more air into the engine"


"

Is higher octane fuel worth the extra cost?

If your vehicle requires midgrade or premium fuel, absolutely. If your owner's manual says your vehicle doesn't require premium but says that your vehicle will run better on higher octane fuel, it's really up to you. The cost increase is typically higher than the fuel savings. However, lowering CO2 emissions and decreasing petroleum usage by even a small amount may be more important than cost to some consumers."

talk to the person doing the tune.

in my 04 imp its supercharged and requires premium. i dont use premium and run mid grade, the reason it need a higher octane is the higher compression ratio of 9.4:1. i still manage around 30 mpg if i keep my foot off it and dont race anyone. if i run reg i run the risk of ping or knock, but the computer will compensate and retard the timing. but like we mentioned before the more timing the more power. but if the tuner advances the timing past a safe point then the engine can loose power.