Yep, you're missing something...
Looking in the wrong place.
See the link for OEM instructions:
http://www.diablosport.com/downloads/pr ... ctions.pdf

i need help on what i should i should put all the setting at for my mustang. The current mods that i have for my car are; shorty headers, full dual catback exhaust, cold air intake, and a underdrive pully. Any help would be good. O yea is a automatic.

preditor model # U7146
"Please send me a free ...

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Thanks for taking the time to write all of that. While common sense would dictate that with 87 tune comes 87 gas, if you read said manual you will see that it specifically states on page 2 (page 14 of the PDF file that is downloadable on this site) that premium grade fuel is required for all ...

"87 Performance Tune" is for performance 87 Octane fuel.
similarly, "91 Performance Tune" is for performance with 91 Octane.
The "Performance Tune" is for 93 Octane. It would probably provide the "best performance," but ONLY if you are filling with 93.

So, "which gives the most performance ...