I never insulted you in my original post. I did make you aware that tampering with emissions is illegal. I'm sorry that educating you on this fact came across as insulting, which if you reread the post I never insulted anybody!
In fact the first insult is when you called me a "fool"!
The difference in back pressure with or without a cat in place will hardly have an influence on what the O2 is reading if any. The back pressure a cat creates is a minimal part of the back pressure the entire exhaust system creates which is pretty minimal itself (if I remember right normal back pressure is around 1/2 psi). It doesn't care about how fast the exhaust is coming at it all it wants to know is the difference in oxygen.