I live in a fairly rural area went out to start my truck this morning and saw someone roll out from under my truck. I yelled at the person and ran after him but let's just say I wasn't warring the right attire for a high speed foot pursuit. Anyway a new cat is just out of my budget at this time. Question is if someone in this position was to put a straight pipe in it's place would it damage anything ? What about not having 02 sensors ?