Find a new muffler shop, You don't have to turn the 02 sensors off... I have bassani comp cats and x-pipe and my 02's are plugged into them and I have never had a check engine light from that. If you want to I think I seen a guy on e-bay that sells the mil elminator or something, I didn't read much into it but I *THINK* those shut the 02 sensors off (I could be totally wrong and thinking of something else)