This invention relates to a turbocharger (210). More specifically, the invention relates to an axial-entry type turbocharger, where the exhaust gases are directed to meet the turbine wheel at least front-on, having a variable volume for controlling pressure, allowing for a substantially uniform pressure and uniform velocity to act simultaneously on and around the turbine wheel, while enabling the volume of the turbocharger to be adjusted under predetermined set pressure conditions. The turbocharge includes: a turbine housing defining a substantially axial primary flow duct, a primary turbine wheel (216) mounted along such primary flow duct (214), and a diverter (218) for diverting flow passing thereover into a primary annular flow path directed to impinge the primary turbine wheel (216). The turbine housing of the turbocharger defines a secondary flow duct (222) for directing some flow to: (i) impinge the primary turbine wheel (216); and/or (ii) bypass the primary turbine wheel (216). A secondary flow duct gate (223) controls flow through the secondary flow duct (222) and is movable between a closed position, wherein under low pressure conditions flow is restricted from flowing through the secondary flow duct (222), and an open position, wherein flow though the secondary flow duct (222) is enabled such that operative flow passes through both the primary and the secondary flow ducts (216, 222) under high pressure conditions. The turbocharger further includes at least one compressor coupled to the primary turbine wheel (216) via a primary transmission thereby to transmit drive from the primary turbine wheel (216) to the compressor.