A turbocharger turbine, comprising: a turbinewheel; a housing having housing walls that define a turbine passageway extending axially, the passageway including a wheel chamber containing the turbine wheel, the wheel chamber extending downstream from an inducer to an exducer of the turbine wheel, and an outlet passage extending axially downstream from the exducer, wherein the outlet passage defines a diffuser having a diffuser wall that starts from a diffuser upstream end at a diameter close to that of the wheel chamber at the exducer and then increases smoothly in diameter for a transtional axial distance downstream of the exducer to reach a maximum diffuser wall diameter at a maximum diffuser wall diameter axial location, the diffuser wall extending further downstream with the diffuser wall diameter remaining constant at the maximum diffuser wall diameter from the axial location to a downstream end of the diffuser; and a center body within the diffuser, the center body having an outer center body wall forming a de-swirl passageway within the diffuser wall and forming a rotationally symmetric periphery of the center body, characterized in that the center body is supported within the diffuser by one or more de-swirl vanes extending between the center body wall and the diffuser wall, and in that an upstream end of the center body has a diameter that is substantially the size of the diameter of a downstream end of a hub of the turbine wheel, wherein the de-swirl passageway comprises an increasing mean diameter of flow from the upstream end of the center body to a leading edge of the one or more de-swirl vanes, wherein leading edges of the de-swirl vanes are located in close axial vicinity of the maximum diffuser wall diameter axial location and a maximum center body diameter axial location, and wherein, downstream of the maximum center body diameter axial location, the center body wall reduces smoothly in diameter from the maximum center body diameter axial location to a distal tip at a downstream end of the center body. a turbinewheel; a housing having housing walls that define a turbine passageway extending axially, the passageway including a wheel chamber containing the turbine wheel, the wheel chamber extending downstream from an inducer to an exducer of the turbine wheel, and an outlet passage extending axially downstream from the exducer, wherein the outlet passage defines a diffuser having a diffuser wall that starts from a diffuser upstream end at a diameter close to that of the wheel chamber at the exducer and then increases smoothly in diameter for a transtional axial distance downstream of the exducer to reach a maximum diffuser wall diameter at a maximum diffuser wall diameter axial location, the diffuser wall extending further downstream with the diffuser wall diameter remaining constant at the maximum diffuser wall diameter from the axial location to a downstream end of the diffuser; and a center body within the diffuser, the center body having an outer center body wall forming a de-swirl passageway within the diffuser wall and forming a rotationally symmetric periphery of the center body, characterized in that the center body is supported within the diffuser by one or more de-swirl vanes extending between the center body wall and the diffuser wall, and in that an upstream end of the center body has a diameter that is substantially the size of the diameter of a downstream end of a hub of the turbine wheel, wherein the de-swirl passageway comprises an increasing mean diameter of flow from the upstream end of the center body to a leading edge of the one or more de-swirl vanes, wherein leading edges of the de-swirl vanes are located in close axial vicinity of the maximum diffuser wall diameter axial location and a maximum center body diameter axial location, and wherein, downstream of the maximum center body diameter axial location, the center body wall reduces smoothly in diameter from the maximum center body diameter axial location to a distal tip at a downstream end of the center body.