I am wanting to cut off my cats and I need to know if I really have to have the o2 sims for the back o2 sensors or can I run it without them? If I go w/o them will it set off any codes or make my truck run different? Thanks for future advise!

 

oh hell yeah it will. You either need to get o2 sims or delete the codes for the back 02 sensors with edit. Your truck will run like crap becasue the computer wont know what is going on.