Should up the EPA rating by 1-2mpg due to the higher rear gear ratios allowed with the 6-speed as it has a very low 1st gear.
I know you discouraged dropping the 6 speed into an 08 for economic reasons, but what do you think would be the effect of doing that in an 08 with a lower ratio? I have 4:10's (which I love and am proud of). Would it be too much, or would it pull like an animal? Perhaps it would make the overdrive too inefficient?
When I factor the ratios I show that right now my 1st gear is at 12.55:1, a 6 speed w/ 3.42s is at 13.77:1, and the 6 speed with 4.10s is at 16.51:1. Sounds like a huge difference. Then over drive went from 3.20:1, to 2.28:1, to 2.73:1, respectively. Which does not sound like much. But does first gear kill the idea?