Device placed within the exhaust system used to catalyze pollutant gasses found in exhaust gasses. Is normally located after the exhaust header, but before the muffler. Can be configured as 2-way or a 3-way: the 2-way affecting hydro-carbons (HC) and Carbon-monoxide (CO) gasses; the 3-way affects Nitrogen Oxide (NOx - do not confuse with Nitrous Oxide or NO2) as well.

history | excerpt history