Exhaust mods are next to worthless on an EcoBoost with a tune, unless you are running something significantly different (bigger turbos etc) and even then it's mainly the downpipes. The reason why dynotunes aren't mandatory with a stock EcoBoost car is that everything is speed density. There's no MAF to tweak or anything of that nature. The VE model doesn't change so you are mainly dealing with fueling, spark, and boost (via torque limiters and other settings).
* 2017 Fusion Sport, 12.7 @ 108 mph tune-only (early tune of mine, bad trans settings), full trunk w/ lunch, and dirty paper air filter
* 2014 SHO non-PP, 12.4 @ 111 mph tune-only, all day long with dirty paper air filter and worn out 30k RS-As