If you haven't calibrated the EM2 fuel flow yet, the GPH reading does not mean anything.  Don't make any decisions based on that reading.   Calibrating the fuel flow is the most difficult and time consuming parts of EM2 setup.   That's the down side of doing it with such an inexpensive flow sensor ($0.00) since it has none.   The other option is to use a Floscan flow sensor with the EM2  but they are pricy.

  At 30" of manifold pressure and best power mixture setting and 6400 RPM you should get a fuel burn somewhere around 15 - 18 GPH.  The exact amount will depend on other factors like exact mixture setting, your intake manifold, exhaust system, air temp, etc.

Tracy Crook