I have 1997 civic hx and want to get after market headers but all the ones ive have 1 o2 sensor bung and my stock ones have 2 what do I need to make after market ones work

 

Its not hard for an exhaust shop to weld on another bung on the header, you can buy the bung or just have the exhaust shop provide it and weld it on.

 

All the aftermarket D-series headers I've seen have 2 O2 sensor bungs, one at the top of the headers and one on the downpipe, near where it connects to the cat. They always have a plug in the downpipe bung so maybe that's why the ones you see appear to not have it. One thing that bothers me about the cheap aftermarket D-series headers is that they don't have brackets to support the downpipe. It's a good idea to rig something up or else the welds will have too much stress on them and could crack. Btw, just looked up headers to confirm the two bungs and wow! The Chinese stainless headers have shot up to $130+! Glad I got mine when they were $60 shipped.