A catalytic converter cleans the exhaust gas from your engine, helping reduce the amount of particulate an engine emits. The term "C.P.S.I." refers to cells per square inch.
A catalytic converter is mounted inline with an engine's exhaust and helps reduce the toxicity of the emissions. It has a ceramic honeycomb with holes, or cells, aimed at increasing the surface area for the exhaust to react with the catalyst. Products of combustion from an automobile include water vapor, carbon dioxide and nitrogen gas, which are considered natural. The bad pollutants are nitrous oxide and carbon monoxide. These are the emissions that catalytic converters aim to reduce.
There are two catalyst elements. The first element acts as a reducer; it will take the nitrous oxide and reduce it, or subtract the oxygen, to create nitrogen gas and oxygen. The second element is the oxidizer, which will take the carbon monoxide and oxidize it, or add oxygen, to create carbon dioxide.
A high C.P.S.I. count guarantees a higher surface area for the catalyst to work. However, one must also consider the catalyst element when judging quality. A combination of a good catalyst element and a high C.P.S.I. count will keep emissions low.
