So i was installing a a/f gauge the other day. I was gonna wire it into the ecu for the sensor wire, but then i was talkin to brad, RiceBurninVtec, and he was telling me how all he did on his was wire it directly to the o2 sensor in the header. So i go out this morning to finish hooking everything up...there is no o2 sensor in my headers lol just the empty hole where it should go. Is this hurting my car by not have this sensor? And about how much are they to replace? Thanks