Did that way back when I had my LT1 T/A. The sound was raspy as hell, and daily driving turn into shit, do to a nice loss in bottom end. Fuel milage went straght to hell, especially once I got the medium stall converter installed. There was one up side. Well, two actually. Sound at WOT. It was off the hook. Sounded nice as hell, even flowing through a stock muffler. Second upside was the performance at WOT. Pulled really well past 4k rpm. Seat off the pants difference. Eventually I had to put the cat back on, since it was time to smog the car, so I installed Car Sound cat from magnaflow. It felt like I lost about 2 wheel hp up on top, but I got so much torque back, it did not matter anymore.
Lesson of the story is: replace cats with either high flow cats, or bullit resinators.