The 2011 suspension is vastly improved over previous years, so there's less need to do sways/endlinks and/or springs/struts. You used to get a huge improvement, but from everything I've heard now, it doesn't make the big impact on your handling that you used to get. However, if you get some Whiteline, Cobb, or similar high quality swaybars and endlinks, it will definitely improve the handling, but at the price of a harsher ride. After that, I'd look at springs/struts.
I'd also consider changing your rotors and pads, but I personally find that hard to justify if they're pretty new. You just don't get much for the stock parts when you sell them. Some slotted rotors and good pads would be a good change to help stop the power better.
And if you're interested in things other than performance parts, I'd get some new speakers/amp/head unit. The stock units are garbage!