If this can help anyone else I figure it's worth it to post it here. I had the right/passenger bank running richer than the left. I had been chasing my tail for a while now. I put my wideband next to the narrowband, then put the wideband on the leaner side before it dawned on me what was happening. With wideband next to the narrowband it correlated well, but on the leaner side the wideband was not only lean but bouncing back and forth lean. So I figured exhaust leak on the lean side, so I finally put a leaf blower in the exhaust and sprayed soapy water on everything. Found the lean side leaking badly but also the other side also at the ball and socket joint from shorty header to y-pipe. So it when I got my BLMs to 128 it was actually pretty rich-which the plugs showed also. Over time and engine movement the ball side/header side got worn and the y-pipe socket was worn also. Wouldn't matter if I put high temp RTV or tightened it more. So I've got it all apart and new headers on the way that I'll have converted to V-band joints and a short flex pipe on each side of the y-pipe to help absorb movement. Tuning should go a lot smoother after that!