Ah, "performance enthusiasts."
That is to say, people who huff paint, apparently as their occupation.
I like Tony Raine's idea of taller tires as a test for gearing changes. It's easy enough to do. I personally can vouch for a modest tire size change helping MPG by changing the gear ratios.
Either way, changing out the rear end isn't going to cause any problems. Ford's Fox platform is the automotive equivalent of Legos, so it's easy enough to swap rear ends (and transmissions and engines) around.
__________________
|