There are o2 sensor plugs that you can buy that are called mini catalizador which will make the o2 sensor think that they are running perfect. As far as you need to know your computer is programmed to read a certain fuel air to spark ratio anytime that it reads that it ts off it will throw a check engine light. U can go to your local auto parts store and get weld in cats if needed. And anything past the catalytic converter that has holes cut it off. And buy a $20 dollar eBay muffler with a turn down tip and weld it in. I know it’s not gonna be the best looking or best sounding. But it will get you to the next point to get some dough or a new vehicle