Abstract: The invention relates to a turbine housing comprising a housing (2) body having a first end (8), second end (12) and a central region (4), wherein the housing body comprises a bore running therethrough, and wherein the bore tapers from a first larger cross-section at and/or in the region of the first and second ends to a second, smaller cross-section towards the central region. The turbine housing may also include a fluid flow restriction means arranged (34, 40) in use to restrict fluid speed, direction or location within the turbine housing.