I know some of you are capable of making these calculations, and at one time I probably knew, but have forgotten now If a two bladed 36" mower has a 13hp Kohler, which spins at 3,350 RPM and turns the blades at 15,000 FPM, then how fast would the blades spin at 3,600 RPM? How fast at 3,750 RPM? I am getting a John Deere GS30 walk behind (fixed deck belt drive) with the above specs and am quite sure it would perform much better with higher blade speed. This machine is unique from other commercial 2 blade walk behinds (which have overlapped blades) this one has timed blades! They sit side by side, no overlapping. The only thing preventing them from hitting each other is a timed cog belt. Don't see that as a problem unless you hit something immovable (which rarely happens for me). Actually there is a good side to it too- the trim side blade is closer to the drive tire for much better trimability, especially on a belt drive. Thanks if anyone can help me!