I drove my cobra with no cats, and dumped flowmasters, for several years, with no problems with the law. I am thinking of having a system built for mine, removing the rear cats, and running duals to the back, but keeping the stock pipe and muffler for inspections, if need be. Then again, I still have the factory mid pipe, from my cobra, lying in the garage. I just can't decide based on u tube, for the muffler(s). I rarely see a crossfire around here, let alone one with exhaust mods. Guess I need to go to a meet sometime.