Tune Update - FA20 E40

This tune update is for existing FA20 (2015-2021 WRX) customers who want to get an E40 map for their setup.

Blending for E40 is both safe and effective on these cars.  To blend for E40 you'll mix pump gas and E85 to a 60/40 ratio, meaning 6 gallons of E85 per 4 gallons of premium fuel.  You don't have to mix perfectly, just close to that ratio. 
 
You do not need an upgraded in tank pump for doing E40 on a stock turbo setup.  For larger turbo setups we recommend having an upraded pump and using our E60 tune option.
 
We do have a good amount of adjustment in the tune to handle variance in the blend so don't worry about this more than just following the suggestion above. You can also install an Innovate or similar ethanol gauge to monitor the blend in your tank if you wish.
 
Blending for E40 works the same for 91oct or 93oct fuel so no need to worry about that as long as you are using premium fuel to blend with. 
 
If at any point you feel you may have blended to far in the wrong direction, don't worry, just drive the car easy until you can add more gas or E85 to correct things close to E40.