I am a GM technician in Calgary that understands the heated oxygen sensor system that monitors catalytic converter efficiency. I recognize that cat removal is illegal, sets dtc's and voids warranty. Ive seen many products for sale to supposedly remedy these problems, and i understand how they operate. I want to know WHICH PRODUCT IS THE BEST??? for avoiding a DTC and check engine light after removing the catalytic coverters knowing that the air fuel ratio in OBD II cars normally fluctuates slightly above and below 14.7:1. There are quite a few products to choose from out there. Want to know which one is the best. Thanks for the advice.