yea right now i dont have an 02 sensor in there.. i drove it yesterday n didnt seem to have a problem but im sure it does somethin that u mite not notice an fucks with emissions im sure an gives the check engine light an another ecu code.. on another forum i asked the same question, and someone told me that 1 of the o2 sensors you wont need, which is the one with the green plug, an the one with the white plug is the one u plug into ur new header an into the socket that u unpluged near the engine, follow me? .. well i havent tried it yet, havent had the time i had to work today an was with my girl before that.. so i will try it tomorrow wen i wake up, an i guess you could try it to if u get around to it, knowin me i prolly wont lol but if i do an it works ill let u kno, an if u try it an it works plz let me kno.. or if u find another way around it