IF you could install headers you might need a tune.
But you can't, so that will save you some money right there. The 2012 and newer V6 Camaros come with a revised engine, code named LFX. The exhaust manifolds are integrated into the block, which means no aftermarket headers.
See here:
http://www.camaro5.com/forums/showthread.php?t=306766
You may want to post your questions in the LFX section instead of the LLT section.
You shouldn't need a tune for an axle-back exhaust system (essentially changing the mufflers/tips), and probably not for a catback system, either, although eventually after you do whatever other mods you plan to do (cold air intake, ported throttle body, etc.) you may want to tune the car to get the most out of your mods.
Remember, tuning voids your powertrain warranty.
PS--Get a catch can on there as soon as you can afford to. A little searching of this forum will explain things further for you.