A system for treating exhaust gases from an engine is described. The system includes, the exhaust gases routed from the engine to atmosphere through an exhaust passage, the system comprising: an injector directing a spray of reductant into the exhaust gases routed from the engine to atmosphere; an exhaust separation passage that separates an exhaust gas flow received from the engine into a plurality of separate exhaust gas flows; a plurality of oxidation catalysts, each of which receives one of the plurality of separate exhaust gas flows; a flow combining passage that receives the plurality of separate exhaust gas flows and combines them into a re-combined exhaust gas flow; a turbocharger that receives the re-combined exhaust gas flow from the flow combining passage; and a selective catalytic reduction catalyst positioned downstream of the turbocharger.