A turbocharger system having a compressor housing containing a rotating compressor wheel with a plurality of impellers that define an impeller passageway from an inducer to an exducer. The compressor housing includes an annular upstream housing-portion forming an upstream shroud-wall, and a downstream housing-portion forming a downstream shroud-wall. The a rib supports the upstream housing-portion with respect to the downstream housing-portion such that they are respectively disposed to form an annular bypass port into the impeller passageway between the upstream and downstream shroud-walls. The rib extends along a non-axial path within the bypass passageway.