Note peak smooth water RPM and throttle response, shoot for 7000RPM. An out of the box Concord 13/17 with stock nozzle is too much for anything less than a low port 771. Raise the trailing edge to 1.3"-1.4". from the blade above and bore the nozzle. It will feel like adding 10HP. Some port work will net even better gains when the pump load is low enough. A 61X exhaust port needs to be 20% larger than stock to make full power at 7000 RPM.
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