Ok, so I had a custom exhaust installed by a dealer and sadly as I was washing my 8ball, I accidentally dropped it and got a couple scratches in my lower pipe. I took the lower pipe off myself to send it off to get re-coated and when I tried to take off the o2 sensor I noticed that it was almost impossible to remove. I finally got it off, but the idiots at the dealership that installed it completely cross threaded the o2 sensor! I contacted them and they told me they would replace it but I'm doing the installation myself this time. So my question is the following. Do I have to use a lock tight or some type of teflon tape when installing the 02 sensor? Am I supposed to use a lock tight with the exhaust nuts? Any inputs would be greatly appreciated!