Wanting to install some OBX longtubes and I see in the pictures that there are 3 bungs per side of pipe. I understand you have an oxygen sensor before and after the cat what is the one after those two for? Also what is needed to plug the air/egr fitting? I asked if anything was supplied to plug it and was told no.

 

That would be good for an A/F ratio gauge if that's what it's for ?

 

there are 6 bungs, I pluged one, installed the 4 factory sensors (at least it looked good) and installed a wideband in the other