That is a reasonable question. I have mowed with this mower for 8 years and know how it normally sounds. It is kind of hard to explain, I guess it just sounds different then it did before, higher pitched maybe, less powerful and faster. I have to run it just below where it is recommended to put the throttle when the blades are engaged, other wise it runs much faster when I engage the blades than it used to. It doesn't bog down though, when it hits higher grass but when I pull onto the gravel drive it seems like it takes a longer time for the engine to make the adjustment to not hitting any grass. Does that make any sense at all?