Yesterday I went out on the river it was cool in the am. I got 5000 rpm's out of it normally I only get 4000 - 4200 but no more speed. I only have a 307 Oldsmobile engine. I am guessing that the Impeller is the original A cut. I am guessing that I am out of the torque range with that little motor but still should of got a few more MPH. There was a little chop on the river so I should have been getting the best speed out of it. No more going down the river than up it either. Just curious on everyones thoughts on this. Thanks