Have you tried adjusting motor height (usually a big screw in the bottom of a pistol-grip or hole for hex key)? 1. Good Mosfet/ECU itself wont care what motor you are running. 2. Even 22k originally would be considered "Hi-speed", because stock is usually 18k. Though nowadays its hard to find after market motors under 20k. 2. Unless your trigger contacts are damaged, don't bother replacing them. It wont impact performance with FET. 3. Imo, if your current motor is fine, you are better off investing into a Lipo. You'll get a lot better trigger response, increased ROF and so on. Rule of thumb is - don't bother with ECUs/wires/connectors/motors if you are running NiMH, the battery will be the weakest link (why are people even running NiMHs nowadays?). Plus Lipos are fun - they can act as smokebombs . If you don't want such fun - get a LiFe.