Aircraft performance is affected by many variables -- temperature, wind, altitude and weight are by large the largest factors. Weight is the only attribute which we do have control over -- even if it happens to be taking less fuel or leaving behind a few bags to ensure the safety of the flight. The other option for gaining performance, is shedding a few pounds off the empty weight of your aircraft.

I have been trying to collect the empty weights of the bush hawks so that we can compare apples to apples, and oranges to oranges (or better put in our context, amphibs to amphibs).