i got a question . i got a APEXi N1 turbo muffler and i was gonna weld a 3 inch piping to it connecting to a 3 inch downpipe ( any recommendations for up pipe and down pipe ? ) but i was looking at a diagram and i see that there is a O2 sensor on the mid pipe . what do i have to do with that ? CEL fix ? make a hole in the 3" pipe ? help me out guys . thanks

 

most downpipes for our cars replace the midpipe, so you wouldnt need to worry making your own 3inch midpipe. bring your muffler to a shop and ask them to fabricate a catback for your car. helix up/down pipes are nice.