Pool pump is a Hayward Ecostar SP3400VSP. Current motor is a single-speed Century 1.25HP (Model HSQ125). I am replacing it with a variable-speed Century VGreen 1.65HP (Model EVQ165). Do I need a new impeller and diffuser due to the change in HP? Inyopools.com indicated I could use the existing impeller and diffuser, but my water flow would not be at the rate of a 1.65HP. Anything else I should know?