System and method for increasing the temperature of gases within an exhaust of an internal combustion engine

Reformate gas is supplied into the exhaust 4 of an internal combustion engine 2 at a location upstream of an oxidation catalyst 6 and an ignition source 14 is provided either upstream or downstream of the oxidation catalyst and upstream of further exhaust gas treatment devices 8 for igniting the mixture in the exhaust to provide rapid heat up of the oxidation catalyst 6 and further exhaust gas treatment devices 8. In a further embodiment reformate gas is injected into the exhaust 24 upstream of a turbocharger 26 to increase turbocharger boost pressure at low engine speeds.