Exhaust system for a dual-fuel engine that is provided with a first fuel and a second fuel. The exhaust system includes an exhaust passageway, with an exhaust treatment component provided in the exhaust passageway. A thermal enhancement device communicates with the exhaust passageway and is located upstream from the exhaust treatment component, wherein the thermal enhancement device is operable to raise a temperature of an exhaust located in the exhaust passageway during a switch between the first fuel and the second fuel that is provided to the dual-fuel engine. The exhaust treatment system can also include a by-pass pipe in communication with the exhaust passageway that by-passes the exhaust treatment component, wherein during combustion of the first fuel by the dual-fuel engine, the by-pass pipe is open. During combustion of the second fuel by the dual-fuel engine, the by-pass pipe is closed.