[dcb]

I'm only guessing, that it is running lean and can't compensate anymore on e10. I don't know that hotter spark has to cost a lot (used coil off ebay/boneyard). but you are losing money daily, if you can figure out a combination that works then you will be in the black in no time, assuming you don't go overboard on the experiments.

so more fuel pressure means more fuel, less lean, less testing of the limits of the ecu. Can you measure your current fuel pressure? Lets just stick with one car, i.e. the metro.