Im confused i recently got the
4-2-1 headers from SR, and it said that it only came with one O2 sensor connection. My car has two, and I know i need to drill another hole to connect the other O2 sensor. The problem is, I don't konw where. there is no more collection point for the first O2 sensor to get a mass reading. I don't want to plug it into one pipe because there may be different amounts of air/fuel mixture coming out from each port of the head. where should the O2 sensor be put in order to get an accurate reading? any suggestions?

 

The first o2 sensor has to go where all the 4 runners meet, the 2nd goes behind the cat ( you better be putting a new cat in ) the first o2 will rach the hole cut in the headders if you lossen the wire harness it attatches to, the 2nd o2 you may need to extend it.