Civic EG

whats up, so i finally found cheap insurance, went to go get my hatchie emissions done and it failed, the guy told me its bcuz i have aftermarket headers and the O2 sensor is only reading one cylinder, so i moved the o2 sensor to the downpipe and it still failed, now he says its prob my cat converter, 200 fora new cat and to put it on, i think i might just go get emissions done under the table for 170, opinions?

Moving to engine general since this is a technical problem and not a thread about the build of your car with pics.

Don't listen to some clown making random guesses. Take the car and have it accurately diagnosed instead of wasting your money by throwing parts at it.

There are so many different ways a car can fail smog. Without the actual numbers all anyone online can do is guess.