Depends on the catalytic converter.

K-jet usually didn't have catalytic converters. The KE-jet had.

There was this guy called Paul Wurm who invented an aftermarket catalytic converter which meets and exceeds the toughest emission laws.

Kind regards
Eberhard
(MY 84 230 E with K-Jet which meets european emission laws mandatory for new cars MJ 97 and younger)

BTW: Good night now, it is three in the morning)