A diffuser assembly is disclosed for conditioning the effluent of a centrifugal compressor. The diffuser assembly comprises an annular conduit, a first set of vanes, and a second set of vanes. The annular conduit comprises a first wall and a second wall displaced from each other and cooperating to define an inlet, an outlet, and a passage extending from the inlet to the outlet. The passage has a first linear portion, a curved portion, and a second linear portion. The first set of vanes are positioned in the first linear portion of said passage. The second set of vanes are positioned in the curved portion of the passage. Each vane of the second set of vanes curves axially and laterally from a vane leading edge to a vane trailing edge.