rocket fans and all rocket-like fans are great. Do not put thermal tape between the motor and the heatsink, it's a thermal insulator! What you want is thermal paste, but this is not a suitable application for it.
Since it's the stock heat sink it shouldn't leave any air gap between itself and the motor. If there is an air gap, I'd consider removing the "heatsink" (at this point it's more like a heat retainer) and let the fans blow directly on the motor can
Since it's the stock heat sink it shouldn't leave any air gap between itself and the motor. If there is an air gap, I'd consider removing the "heatsink" (at this point it's more like a heat retainer) and let the fans blow directly on the motor can