Just noticed this
http://tetraboost.com/ It is supposed to help negate ethanol up to 15% and can also give an octane boost almost up to avgas levels depending on the mix used. It costs £140 delivered in the UK and treats 700 litres.
I am using Frost Ethomix at the moment but it does not contain an octane booster. Lead additive has to be purchased seperately.
Jim