Ethanol

I notice my 360 magnum runs way more smoother on the ethanol free 91 octane fuel then it does on the 91 octane with 10 percent eathanol. There is a cenex in my aera sells 91 octane eathanol free so thats what i run.
And i have access to ethanol testers that tell ya how much eathanol is in a fuel, i test the cenex premium every couple months to make sure it truely is ethanol free.