Better fuel mileage can be a result of O2 sensor control, possibly the EHA change wasn't the only reason for the difference.

Adjusting the fuel mixture so the O2 sensor can work is the key to mileage.

FOR better acceleration having a slight greater difference between system & control pressure is the key.

FROM Bosch the EHA is adjusted to have 0.400Bar differential warmed up with NO lamda control.

Having 0.399Bar means less acceleration. And having 0.401Bar differential and more means better acceleration.

Slight adjustments can allow for better acceleration, but will cause poor mileage IF the O2 sensor can't adjust the mixture in closed loop.

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