As far as which o2 sensor I plug into, Mike Bell will actually be tuning them car and he had me put both of my o2 sensors in the down pipe (hood dump now lol) so they are in the same pipe side by side so it shouldn’t matter which is plugged in to which correct? And he also gave me the part number for the longer o2s I got them. Just gotta try to open the harness and finangle the factory plugs up there so I don’t have to extend anything