Well it turns out I was tricked into buying tunning pros s14 headers for my 1992 s13 so I got a couple questions. There are three ports in the exhaust one is for the o2 sensor what are the other two for? I also am wondering if anyone knows if a s14 o2 sensor is compatible with an s13 apperrently the threads arend going to align. But other than that it seems to be ok the exhaust works well but I doubt its street legal but I want to try and connect everything so it comes close at the least. One last Q, If anyone can answer it, anyone know the thread size on the s14 o2 sensor?

 

you can still use the headers. the three 'ports' in the exhaust are 1.the egr tube on the side of the header, 2. the next down is for the o2 sensor in the original position, 3. on the collector pipe is where the o2 sensor should be relocated due to changes in the epa regulations...so plug the original sensor hole up and extend the wire to the collector pipe...next thing..***king search for 'header install' and you will easily find you answers

 

thanks for the help but you didn't say much about the third port which is something that is realy strange and doesn't make much sense. Its call an AIV conrtoler and it senses when the exhaust loses pressure and starts taking air from the intake and pumps it into the exhaust. This thing is very anoying and sounds useless do you think its nessesary for anything? Cause if not I'm removing it.

 

save the environment and keep it on. its part of the emmisions systems i believe.

 

It's actually the EGR (which is on the side closest to the top), o2 sensor (I believe this would be the second hole from the top), and the third hole is the AIV. The AIV can be removed, many people do it just to free up room, shouldn't have any real side effects but you may not pass emissions without it.