Abstract: Provided is a catalytic converter (1) for cleaning exhaust gases in pre catalytic converter vehicles. The catalytic converter (1) comprises a body of an elongated shape having a first end portion (11) and a second end portion (12). The first end portion (11) comprises an exhaust inlet (110) through which exhaust gases from the engine enters and the second end portion (12) comprises an exhaust outlet (120) through which the treated gases exit. The body has an internal space (14), wherein the internal space (14) at least partially comprises a plurality elongated passages (140) which are in fluid communication with said exhaust inlet (110) and exhaust outlet (120), the passages (14) being arranged at a density of 100-200 cells per square inch (cpsi).