Muffler and headers for 2013 v6

I'm looking for some headers and a muffler/exhaust system that would help with mpg. I've done some searching but I can't find peoples mpg results with headers and exhaust most the times. I don't plan on putting on an intake or supercharger or getting wild with it I just do regular driving and on the weekends I like to drive on the beach or in the woods. In leaning towards keeping it stock cause I haven't found any good data supporting me getting something different. But if anyone has had good experiences with something I would definitely be interested in it.

 

I don't think any exhaust changes will gain you mpg.