I have a 2006 Buick Lucerne CXL 3.8L v6. My dad bought it about 6yrs ago & did what he could, took it to shops he trusted when he couldn’t do the work. I’ve had the car 2yrs now and Dad just told me one shop completely removed the catalytic converter. Is this common? Besides throwing a code or 3 for the catalytic converter (that doesn’t exist), should I expect issues related to this?