Hey guys, thanks for all the input. I'm still a little lost, but I'll read things over again and ask my friends. Yeah, my car is really weird... it's 96 Civic EX, but I haven't seen any other EX's with 2 O2 sensors where mine are... I've been thinking it was swapped before I bought it used? (at the time I was clueless about cars). The sensors on the stock header are on the top of the manifold and one vertically under that where the pipe bends 90 degrees. I can't remember if there was one before, after, or in the cat... maybe in the cat? I don't know because I'm up at a university right now and I left my car behind at home, haven't fiddled with it in a while. Hopefully that'll help someone out figure out this problem?