You can't stack on the Fords. Tell your friend to buy an SCT or prepare for blown HGs and/or tranny.
A good custom tune will be the better all around choice in my opinion.
my bro stack his edge with bully dog...it was fast! but the tranny was gone within 5 weeks! SCT all the way
Why not have him stack the SCT with it? You can probably find someone capable of tuning an SCT to work well with the Edge so that the Edge doesn't eat his trans. Won't get much more power, but atl3east you'll save his trans. Another option would be EFI live.
Stacking other tuners/chips with an Edge is a definite recipe for problems as mentioned above.