im building a true dual exaust system. the only thing i dont know about is where to put the o2 sensor fitting. it has an H-pipe from the headers back. can someone tell me where to put it?

 

Usually goes into the H pipe. If its a model specific h pipe it should have the threaded hole allready. But you will still get the check engine light because of the different gas readings without the cats. U will need a resistor for it or it will read a rich condition.

 

i have 2 high flow cats. will that still effect the check engine light?