An assembly can include a turbine housing that includes a bore, a wastegate seat and a wastegate passage that extends to the wastegate seat; a bushing configured for receipt by the bore; a rotatable wastegate shaft configured for receipt by the bushing; a wastegate arm extending from the wastegate shaft; and a wastegate plug extending from the wastegate arm where the wastegate plug includes a profile, defined in part by a portion of a torus, for contacting the wastegate seat to cover the wastegate passage. Various other examples of devices, assemblies, systems, methods, etc., are also disclosed.