So ive been doing some research online now and ive talked to a few mechanics, and the responses ive gotten are pretty mixed on this subject. Im looking to do a complete redo of my exhaust system. Mostly cause its all rusted out. Ive already got some long tube headers on the way in the mail. The real interesting part is here: The 02 sensors. I know for a fact that engine and the computer DO need the pre-cat 02 sensors so that it can constantly adjust the air/fuel mixture. So ill be putting the pre-cat 02 sensors into the new pipes for sure. That leaves the post-cat 02 sensors. How necessary are they. Ive had a mechanic tell me that they are really only put in place to make sure that the cats themselves are working. They dont do anything for the engine. How true is that? Alaska doesnt have any emissions testing and i dont plan on taking my truck out of state any time soon, so if i can just drop the cats out of this i would be pretty happy. But i want to be sure about it though. Does anybody know anything pertaining to post-cast 02 sensor functionality? Thanks!!