I am getting my new exhaust in a couple of days. It is RB header, pre-silencer, and cat-back. I was wondering if I should put in a new O2 sensor with the system? I still have the original one in the car now. Also how can you tell that one is going out or is not working right? Thanks

 

Were do you get the O2 sensor? I got a price quote today of about 35 dollars when i ordered my fuel filter for 17 dollars.