its all about what you want out of it and the gearing of it.
The ford spec 5th is .85 or so and 6th is .63~ (around there)
in your 5 speed final 5th gear is around .68 (whats that only .05 dif...) basically its not much difference in that respect, but a little lower 5th is not to bad overall
the viper/vette spec T-56 usually use .50 final drive that gives you much better gas mileage and lower rpms cruising oh why ford why didnt we get that
the 2010 gt500 FINALLY did in their 6 speed...