Is yours running rich? With both sensors tapped into one line on mine I was getting like 15 miles per gallon and it ran like ass. I know that the secondary should go to pin C8 on your PR3 ECU but Im not sure about the primary. I sent Hasport an email a while back and they wrote me back with that info. They said that the primary should go in the third runner and that the secondary should read in the fourth runner. Then again they also said if it runs funny, I might try switching them around. So all in all I guess using the bung on the collector that my header came with is out of the question. Ill just throw an old spark plug in there to plug it up.