LPT - if you are having the catalytic converter replaced on your car, especially an older one, ask for the old one back. It can be worth $200-$1500 at a scrap yard

Catalytic converters, especially on older cars can contain a lot of precious metal. Do not let the mechanic offer to "trash it for you" insist that you want the old one back and call a few local scrap yards to see what they would offer you for it. For example, an original cat from a 2008 prius can fetch $1000-$1500 from a scrap yard, so dont let the mechanic keep that money when it belongs to you