Comparable power from the 160 to the 170, the pump reference has been removed, have not dissasemble the pump yet, as there is no need to. The engine is still identical to the 175 but the pump reference hose, the ignition is half the size, and it seems to have an output for a tachometer, but I have no instructions. It should go well with a 21, 20.5 x 10 is ok but not enough prop.