axial inflow and radial outflow turbine

[nictech]

I am working on design with radial outflow axial turbine, where the exiting flow has to flow radial outwards and then collected due to the downstream components attached to the shaft (ignore limitations due to hot gases).

Would it be best to use a volute or just a plenum collector? I judge that due to lack of swirl component in the axially exiting flow, more pressure loss will result if a volute is used. ANy thoughts?