4cyl tranny is only rated at 240ft.lbs of tq compared to v-8 at 300ft.lbs of tq.
The 4cyl gearing sucks in my opinion, I like to have a usable first gear and decent overdrive.
My friend had a 4cyl tranny in his gt and then switched out to a word class t-5 from ford racing with 2.95 first gear and .63 overdrive and the car is way more fun to drive now and gets great highway fuel economy. He also has either 3.73 or 3.55 gear in the rear end too.