Harold,I was wodering myself about them being illegal.Mabe they were just hasseling him.
But a factory installed systym has different rules than any modifacations.
The motor he has in it didn't have cats but the car itself came factory cats so the regulation applied to the body,not the motor.Anyway now he got hobbiest plates wich makes the rules different again,I'm not sure how but my son know's,I guess it's alway's something!