I haven't 100% decided what I'm doing with the exhaust yet. I'm thinking either magnaflow (cuz I've done flowmaster a lot in the past and wanna switch it up) or go with the MBRP system from Stylin Trucks. The reason I like MBRP is because it's a system you can install in your driveway (and I'm a do-it-yourself kinda guy) and from the clips I've heard on YouTube it sounds great.
Now, as far as returns....in all honesty, just doing an exhaust on a stock motor will yield negligible returns other than a better sound. You may notice slightly better throttle response but that's about it. With that said, if you do an exhaust, intake and a blackbear tune you will get a pretty noticeable improvement in both MPG's and HP increase. I hope to have the exhaust on mine done by end of summer and the airaid jr intake by the fall or maybe sooner. Then I'll save up for a tune after that.