all i know is i love my E85. i havent had any probs with my truck and i do see a horsepower changeand the engine runs a hell of alot smoother. the only down side to having the flex feul was when i went to replace the fuel filter i had one hell of a time trying to find an FFV feul filter. took 3 days and a special order. then i go to auto zone and ask what i should do for engine oil knowing if i had a hard time finding a specil feul filter maybe ive been putting the wrong oil inn it too. well i was right, but i dont quite know why, so now my oil changes cost me 70 dollars now. but other than that I LOVE FLEX FUEL