[KingLT1]

As Mike said the flex sensor allows you to run straight pump gas, or E85, or any blend in between. my advice would be to target E60 and just keep it there. The reason being is in the summer you might squeak by on whatever percentage of Ethanol comes out of your local pump(normally E78-80) but in the cooler months you will likely run out of fuel system headroom unless you mix it with pump gas and lower the E content. E60 provides 95% of the gains of Ethanol fuel for most setups anyway. So I would just target that percentage when you fill up. It doesn't need to spot on either. It can be E50-E60 and it will be fine.