Question: is the catalytic converter part of the exhaust system

Answer: Yes, A catalytic converter is an exhaust emission control device that converts toxic gases and pollutants in exhaust gas from an internal combustion engine into less-toxic pollutants by catalyzing a redox reaction (an oxidation and a reduction reaction). Catalytic converters are usually used with internal combustion engines fueled by either gasoline or diesel--including lean-burn engines as well as kerosene heaters and stoves.