I've heard of cars running fine when you take cats out, even though they'll put up a check engine light, and i've also heard of it affecting performance. I cut down my cross member so i figured why not run a true duel. I know other vehicles have a way to bridge out the 02 sensor(not exactly sure what it does) Anyone know of a mod for the silverado's??? Gonnna be an expensive mod cuz NY is real strict with inspections, they are video'd and everything. Costs like 100-150 for an "inspection" and very few shops will do it for you anymore. Any of you guys with true duels, did you move your fuel lines, or just have the pipes run right through that hole in the frame??