I left the two stock o2 sensors after the headers and the wideband in the downpipe. You cannot tune without a wideband. is the tuner going to tune for a maf or speed density? Are you running the stock pcm? Once your ve tables are correct, you shouldn't need the wideband again until you make a change, like turbo, intake, etc. I leave mine connected but don't look at it much unless I'm scanning a run at the track. the wideband unlike your o2 sensors have no communication with the pcm. Its just an input, so you can track your commanded afr vs actual. then the tuner takes this afr error and makes an adjustment in the tune to adjust more or less fuel depending on rich or lean.