Various embodiments for an exhaust gas treatment device for a vehicle system are provided. In one example, the vehicle system includes an engine with a longitudinal axis, where a crankshaft of the engine is parallel to the longitudinal axis and an exhaust gas treatment device mounted on the engine, vertically above the engine such that a longitudinal axis of the exhaust gas treatment device is aligned in parallel with the longitudinal axis of the engine, the exhaust gas treatment device configured to receive exhaust gas from an exhaust manifold of the engine.