You must be in extremely heavy, wet, cutting, but I'm still surprised you hear very much change. You and I both know you can take grass loaded with moisture and it will pull an engine harder than dry grass twice the size. The E-Governor senses load and adjust fuel accordingly, this is why you are not suppose to get the extreme change which affects the sound of lowering and raising engine speed. As you well know, anytime you hear the engine raise and lower speed, fuel economy is being affected. I am really quite surprised you noticed a great deal of change in sound, but with fuel numbers on a new engine at 1.3 gph in heavy cutting, there is nothing terribly wrong. This is an area Generac has excelled in for many years with their engines. They implemented the E-Governor on their generator engines years ago so as additional power is needed the engine could have more fuel added to compensate and prevent rpm lag, this way there would be no drop in amperage from the generator output.