Gas mileage loss after power commander?

All drivetrain, gears, tires, all stock. Read a lot of people saying how the speedo from the factory is off which was the motivation to purchase the speedo corrector. I forget the exact setting, did the bike reading compared to the gps reading and put it into the equation on their website. Speedometer is dead nuts with the gps now. Thats why im thinking it was that far off from stock, that or as previously stated could be the cold with the fuel.