By replacing the CAT with the M4 mid-pipe you will increase the exhaust flow rate which will give you better engine performance, cooler running temperatures and it shaves 10+ pounds! It will require you to cut the stock exhaust to fit the mid-pipe, this is a pretty easy task with a few basic hand tools(instructions included).
Mid-pipe will fit stock muffler or most aftermarket slip-ons.
May require a fuel tuner to get optimum performance.