Gordon454

hey guys um i got a small problem i have bbk shorty headers and bbk off road H pipe that i just installed and i have supper 44 flowmaster mufflers. i have a backfire at 3000rpm when decel and not sure why i have the o2 sencers in and then back 2 i have them lifted off the H pipe with spark plug foulers cause i was told that taking out the cats will make the brain send a code and i dident want that. so a buddy told me puttting 3 spark plug foulers on top of eachother and drilling out the in side will take the code away well there is no code that comes up but i have the back fire could that be because i did that or is it that my o2 sencers are old cause there the stock ones that were in the car when i got it. thanks gord