I too own a 09 SG, and I replaced my stock mufflers with an aftermarket product. I purchased Rush slip-ons, at the same time I had the dealership install a SE race tuner, and a Zippers air kit. I guess I'm more of an idiot than most, I had the dealership install the above things, map the bike then complete a dyno, so that I knew everything was right. I don't follow the idea of spending many thousands of $$$ on a new bike, wanting to make it sound better or run better, then scrimping on a particular procedure to make it better. I know that I have experienced much better performance out of the last two bikes I had, with a trained and experienced technician setting them up, than had I tried to do it myself. Well worth the couple of hundred it cost.
Just my thoughts...:lero