I've been using Star-Tron Enzyme Fuel Treatment. Their claim is the concentrated product cures ethanol problem, stabilizes gasoline for up to two years, cleans valves and injectors, helps remove water, rejuvenates old fuel, and a list of other good things, but NOT an octane booster. My CafeSport has not suffered from tank swell syndrome as far as I can tell. I don't know for sure if the Star-Tron is doing anything helpful, but it doesn't seem to hurt anything, it's not expensive, and readily available at Wal-Mart.