The reason you see 93 mentioned for fuel but can't find it here is because America uses AKI as their octane rating while we in Australia use RON
87AKI = 91RON
91AKI = 95RON
93AKI = 98RON
Now I'm going to be a little less subtle than the others.
If your getting your information about fuel and Cobb and HPF from a guy named Alex/PremHK/Alcam either ignore it or listen to him and don't ask anyone else here.