An aspirator coupled between an inlet of a compressor and an engine intake manifold may include sonic/supersonic expansion curves for both forward and reverse flow through the aspirator. Suction flow may enter a first entraining port coupling an ambient side of the aspirator with a vacuum source during reverse flow through the aspirator, whereas suction flow may enter a second entraining port coupling a manifold side of the aspirator with the vacuum source, the first entraining port counter sunk relative to a nominal slope of the aspirator to reduce flow disruption caused by the port during forward flow through the aspirator. A radial-flow aspirator shut-off valve arranged in series with the aspirator may be controlled to enable or disable motive flow through the aspirator, and motive flow may enter the valve in a direction perpendicular to a motive flow axis of the aspirator when the valve is open.