Ah, probably. The only things I know for sure on the '15s is that it's no longer over axle and the mufflers are welded on. The pipe needs to be cut off to change them.
Does the 5.0 have a "big" resonator? ('14s are kinda small.) I'm pretty sure they'll keep a resonator. Cars have had those for decades.
If you want a group that is all about the '15s, take a look at the forums at 2015+ Mustang (s550) Forum News Blog – Mustang6G | The Ultimate 6th Generation Mustang (S550) Enthusiast Site
. They seem to know a lot about the new cars.