When I got my car tuned, my tuner put a W/B sensor at the end of my muffler for the A/F reading. My exhaust setup: non-catted uppipe, one high flow cat in the downpipe. My question is, does the cat affect the A/F reading? How different would it be if lets say I went catless? I would think that the A/F reading would be off due to the cat burning off unspent fuel. I was just curious. Thanks.