do i need a 4 wire o2 sensor in my b18c swap into a 1990 teg

if i do need one, will a four wire o2 sensor fit in my stock header or do i need to get a 94-95 stock gsr header? thanks for any info.

if you’re converting to obd1, like your sig says, then yes you need to use a 4 wire sensor. Go do a search again, i know you’ve been good about searching…but go back and read some of those posts again, its mentioned a few times that the 4 wire sensor is needed.

I’m not sure if its going to be bad to put the sensor up by the primaries. It was designed to do down in the collector. It might work to use your 90-91 header. But ideally you’re going to want to use a 92-93 header. Or if you want to deal w/ modifying the flanges and what not then you can get yourself a header for the ITR. Like a jdm dc 4-1 or something of the sort.