I was planning on installing a wideband today for later tuning. Rather than replacing the o2 sensor, I was going to weld in another bung to screw in the wideband sensor. I read that it should be installed at least 24" downstream from the block, but before the cat. I have dynatech LTs with cats. Does this mean I should be welding the bung on the header right before it bolts to the cat? Would it be a problem if I just install after the cat? I have read others do that, but does the cat alter the reading? Thanks for your help.