You're lucky you have the 2009, they didn't put a CAT in the header, so you can keep it and benefit from only changing the mufflers. I pulled my header and was surprised there wasn't one. After a bunch of reading i found it was only taken out for '09. I put on the Vance and Hines Twin Slash Rounds. They look and sound great. They are on the louder end of the options. If your not into noise, add the quiet baffles.
Hey, look! 7 responses and 7 different answers, well here comes #8. I love my V&H Monster Ovals...It depends on what you want. These are not loud. They are very deep and unique, but not obnoxious. Kinda pricey though. Good luck, Sir.