99-coupe

ok first of all thanks in advance for the answers that i might get..
well i just got a new apexi ws2 exhaust for my civic ex and i put on a test pipe but both of my o2 sensor broke so i didnt put nothing back in there would that affect my motor or performance in any way apart from low gas milage??
another question got is that everytime i take i hit the gas i hear alot of noise comeing from like the headers the sound is like the air flowing from motor sometimes that sounds more then my exhaust i have some old dc headers u think its time to change them or is something else the problem i just replace the header gasket thing. but the holes were the o2 sensors go are closed (sorry for my spelling only went to school until 8th grade)

koa

If you dont have any o2 sensors that are working, yes it will hurt performance. Your ecu needs those. That noise you hear is probaly from the holes that the o2 sensors go into. I wouldnt think its safe to even run.

96 EX

Ditto, get some O2 sensors but if you aren't going to get them at least grab some bolts to fill in the holes from where they should be.

Vindicator9000

yes, your car will absolutely run like crap without a front O2.