My 2014 is tuned for e85 with a Trifecta Elite tune but without the Flex Fuel conversion kit. I did two datalog runs using E85 from two different stations since I suspected the e85 of one of them was not up to par and submitted them to Trifecta. Proved I was right. Steven at Trifecta strongly recommended that I order the ZZP Flex Fuel Conversion kit because without it, the ECM is "blind" as to how much ethanol is truly in the tank, and is forced to compensate via skewing the fuel trims. Michael confirmed that the ZZP kit will work with their Elite tune. I placed my order with ZZP and the Flex Fuel kit should arrive in a couple of days.
The Flex Fuel Conversion kit also frees you from the anxiety of getting caught on the road with no e85 available near you, or perhaps having to drive far each time you need refueling. This is a bonus as it will also allow me to run other types of fuel (e.g. 93 oct, 106oct racing gas, etc - heck, I might even try avgas, lol) without fear of giving the car an indigestion.
Last, a special shoutout to the Trifecta gurus for their awesome and super fast service.