But I just heard about the possibility of a motor dubbed 'voodoo' which may make its way into the Mustang at some point.
The 'voodoo' is a flat plane crank V8 with twin turbos strapped onto it. What this means is that the crank is positioned to be 180* apart, rather than having each piston 90* with large counterweights.
Ferrari has used this design since almost forever. While Ferrari and other manufacturers which have used this design tend to go with lower displacement higher RPMs, Ford would be sticking with somewhere between 5 and 5.5L.
This could make for a 600-700 hp streetable Mustang with an absolutely insane sounding engine (think Ferrari meets Subaru with turbos).