Abstract: A high speed electric motor drives an impeller to centrifugally induce air flow to an engine exhaust system. The motor is sealed within a noise attenuating cover, and the impeller induces a portion of the air flow to recirculate through the sealed motor chamber to cool the motor. A noise attenuating duct is mounted on the pump inlet. The duct includes an elongated neck of rectangular cross-section extending at an angle from a tubular body, the remote end of said neck being tapered, each side of the neck having a series of parallel inlet louvers, and the body having an internal foam liner.