I posted a thread on installing GT500's on my 2011 V6. The sound is great! Nice idle rumble, great cruising speed (not loud nor any drone), and if you hit the right pedal, you'll notice it, but it's not a cop attention getter.
For the 2011 and 2012's, all the hangers are the same between the V6 and V8's so that's alright, but you will need a muffler shop to cut the back tubes off of your V6 mufflers and weld them onto the GT500's as the "ball" connection for the V6's are a smaller diameter. I've read that the 2013's have different hanger setups, so if that's your case, research it if you go the route of GT500's. The best part? I got them used for under $200.00 shipped to my door, and the muffler shop did the back tube welding AND install for $80.00! Much less than just the purchase of an axle back set of mufflers!
I should note that the GT500 mufflers are heavier than the Stock V6 ones though. I don't know why, as they flow much better than the stock ones.
Here's a couple of pics of the install on my V6 (the left showing the weld, the right shoing how nice they fill the openings):