I ran a custom dyno tune (for 93) with AFD flex E85 kit and it was having a slight hickup when you WOT floor it. Had it on full E85 for 300 miles. It was doing it with 17% to 75% ethanol (E85 here only has 75ish %). But I had no fuel pressure codes because I have upgraded AEM E85 fuel pumps. My tuner says it was the flex kit and that I need to bring it in for an E85 custom tune. He thinks it was running rich at the moment I WOT. So I went back to 93 and havent really noticed the hiccup. Not really sure if it will do it on a stock tune. I havent had the chance to go back and get my tune because my RADTEC oil cooler started leaking after only 4 months of use (Radtec said they will send me a new one asap).. separate story. I will also pickup my handheld tuner so I can switch between 3 maps - stock, custom 93, custom E85. I also have the FAMS tune so I might try the E85 on that tune just to see. Having the E85 in the tank definitely made the m5 pull harder for sure.Has anyone had a detonation issues following the flex fuel mod and tune? A very reputable SoCal shop that everyone would recognize advised against flex fuel and tune because they do not believe any existing products effectively detect ethanol content and then properly adjust timing in real time. They basically said the tune will be optimized for the gas in the tank at the time of the tune which will result in detonation issues when e content drops or premium unleaded is used. Thoughts?