My '09 2LT came with dual exhausts because it has the V6, not because it's an LTZ since it's not.
To swap yours to dual outlets you'll need the valance piece from a dual-outlet car (on any3.6 it is standard, available as option on 2LT and LTZ models) and a way to get twin outlets. I already had dual exhaust so had my boat anchor (factory muffler) removed and put twin resonators on a Y-pipe. Sounds better (not a fart can) and flows better, too! You could do the same. It wouldn't be stock, but neither is dual exhaust on a 4-cylinder.
If you take a look at the factory muffler for the 3.6 you'll see that it sits across the back of the car and takes up a LOT of room. It's heavy, too. You'll also see that they didn't bring the exhaust from the front into one of the ends where it's strongest, but welded an outlet on the freakin' SIDE of it! As soon as it enters the muffler it runs into a dished deflector that forces it to become a stream of gases now going in two directions. When it finally exits the muffler at the ends it has to turn 90 degrees again. Count 'em from the outside. Enter & turn 90, exit and turn 90. Add at least one more 180 for it to turn inside when it hits the end plates. Now compare that to what I replaced mine with. A Y-pipe that splits it with a 45 bend, goes straight through a resonator and into a 45 to the tip. Gentler bends and no real restrictions. From the back it looks like the stock dual tips ('cuz they are) but underneath I now have enough room to put a dead body! (I could work for the Mafia, eh?)
Just my input on choices you have before you dive in.
