Hi guys, long story short: i recovered my stolen honda and found out the thieves took the whole exhaust of my car, catalytic converters are expensive and i dont need to pass any emissions in Oregon state, so i got a cheap exhaust already installed on my honda but its direct, has no catalytic converter nor o2 sensors, so my car is not getting the best mpg 😅 i want to buy the o2 sensors but want to know if what o2 sensors are vital for the fuel/air mixture, the upstream? Can i get away buying only those? I thinks the car should have 4 but im not so sure, id really appreciate if someone can help me out, dont have a lot of money and dont want to invest a lot, just want this car to run decent the way it is now.. Thanks in advance.