Fuel injection has played a major part in reducing emissions. The accurate computer control of fuel and ignition timing has also given us better fuel economy and performance. Most now use a honeycomb type internal construction. The honeycomb style of converter permits the exhaust gases to flow through it much easier so the engine has better performance and fuel economy than with older style converters. These metals cause the exhaust gases to chemically react and form less harmful pollutants.
Catalytic converters work well but can be damaged by a poor running engine.
Temperatures inside the converter soar above the melting point of the ceramic when this happens and the converter starts to fail. The melted ceramic blocks the flow of exhaust gases. This results in less power from your engine and poor fuel economy. Checking for a plugged converter can be done by placing a pressure gauge in the exhaust system before the converter. The oxygen sensor mounting hole is usually the easiest place.