Ok guys here is the deal. I have a 99 civic lx that has just a measly 165k on the clock. My problem is that the original cast exhaust manifold has a crack the size of Texas in it and it sounds horrible. This happend once before and I temporarily replaced it w/ a tube header from some other civic. The problem this made me have was that the o2 sensor that is supposed to go behind that cat went bad on me and the check engine light came on. (keep in mind that on my old manifold the cat was incorporated in the manifold itself). I then decided to weld the old manifold up as best I could (worked for a little while). But now I am essentially back where i started. So.... Here is my real question. Will it hurt anything if I put the same header on that i used previously w/ no cat? I live in Oklahoma so emmisions laws are not enforced like they should be so thats not really a prob. And will the none working o2 sensor really make a difference. thanks for the help

 

if you are gonna run w/o a cat get an o2 simlulator. you will run either lean or rich w/o one, cant remember which way though. but it will make your car run not so well.

but an o2 simluator and u will be golden