Ok got 90 crx with b16, came with 2 o2 sensors in the upper part of header. my dc sports has only the lower bung. So how do i wire this? Thanks guys

 

only use the primary o2 the one with the cream colored plug. atthe ecu bridge if memory serves me correct pins c8 and c16. so that the ecu can read the primary and the secondary o2. one of the two spots will be blank so just pin it and splice to the other pin location

 

no, plug the lower bung with something ( i think spark plugs work, but might get in the way of the flow), and take your header to get two o2 sensor bungs welded just like the oem application.
@ least that's what ive heard from the past.