i have a buddy that has an obd0 pr3 on his crvtec he bought an aftermarket header that only has one o2 bung what would happen if he only used 1 sensor or 1 four wire sensor....do all pr3 obd0 ecu's require two o2 sensors.....what would be the best way to solve this problem....and his wiring harness is from an 90teg i tried to search but the search engine told me to use three words or something...