Johns tune is good as long as he buys his e85 at the same station and monitors ethanol percentage making sure it doesn't deviate from his tune. I had planned on running his chip in my Z, but the ethanol content here in Phoenix is closer to 85% rather than 70% in Omaha. I've had some good talks with Greg D and Jason at ProEfi, and they both warned me about the dangers of an e85 chip tune with varying ethanol contents. I'm torn right now between Haltec and ProEfi stand alones with flex fuel sensors.