Anyone can turbo an engine ... but is the engine, transmission, and drivetrain built for it? Does the turbo carry the factory warranty?
450 hp from a V-8 isn't that impressive? It's more than the 5.7 SRT-8 engine puts out :-D with less displacement too. Even the 6.4 SRT-8 engine only tops the Ti-VCT 5.0 by 20 hp ... and it needed another 1.4 L to do so.
The Ecoboost 3.5 is only rated for 380 hp in the up and coming 2015 Navigator/Expedition (which is still a lot of power).
You're comparing a naturally aspirated 300 HP V-6 that is 31 mpg capable and saying you could get a blown V-6 to do better? I'd hope so, otherwise that would be pretty depressing.
Again, of course a turbo pentastar will beat a naturally aspirated V-8 ... take a turbo to the V-8 and it'll walk all over the pentastar. The more power you start with, the more power you'll get.
An old motor? Ti-VCT engines are barely 4 years old, and American car companies (including Dodge) tend to keep engines around for decades.
And the Mustang is boring and mundane? I'd take it over a Challenger or a Camaro any day.
400 HP 4-cylinders aren't daily drivers, and they still don't match the torque of a V-8
Here's a 2500 hp twin turbo Ford 5.4 DOHC engine in a Ford GT.
http://www.carcraft.com/techarticle...ci_twin_turbo_modular_ford_engine_horsepower/
Show me a Mopar engine that is able to crank out 2500 hp without grenading.