i'm installing a bbk header on my 96 dx and i was wondering if i need both oxygen sensors installed for my car to run right as the header only has a place for one. thanks mike

 

Basically yes, you will need to have both 02 sensors hooked up. Otherwise you will get a CEL.

 

Yes you also need a cat, o2 sim, or OBD1 conversion if you don't want a CEL. If the secondary O2 doesn't pick up a catalyst around it, it will throw a code. I don't think the secondary O2 affects performance though, but you will fail emissions, but without a cat you will fail visual anyways.