my man!!! Yes u did!! thanks!!!Well, the tune determines which octane gas to use for each, thus their naming.
91 = 91 octane tune
93 = 93 octane tune
If you don't have 93 octane fuel readily available then don't run the 93 octane tune. Similarly, running 93 octane fuel with the 91 octane tune won't provide any advantage over running 91 octane fuel with the 91 octane tune.
Hope this helps.