If you wanted to get more performance out of the exhaust, don't worry so much about the size of the piping but look at the restrictions in the exhaust; pre-cat, cat, resonator, muffler. The car isn't pumping that much horsepower to need a 3" exhaust. If you eliminate the restrictions closest to the engine, you'll see the most noticeable of performance gains
if you are looking at a simple change in noise change your muffler. If you want it louder, remove your resonator. If you want rasp, remove your second catalytic converter. If you want F**K TON of rasp, delete your pre-cat and your catalytic converter. A magnaflow muffler has built-in resonators so it will not be that loud on its own. If you are going to want a bit more noise with your magnaflow muffler, i would keep your cats and remove your resonator because your muffler has a built in resonator.