I just tuned a 100% stock 2015 roadster on E85 with ecutek, no mods except it had GTR injectors to provide the necessary fueling. The car used my software flexfuel programming that allows adjustment of ethanol content without the use of a sensor.
There is a dyno sheet if you scroll through, the car made 310 whp.
https://www.instagram.com/p/CAV39eQHZcB/