I am a M6 now but i am going to be changing to a Th400 in the next month or 2. My question is i have a 9" now with 4.11 now an i am thinking that is going to be too much gear but i am not shure. The car will get driven on the street some but mostly only too the track. I am running a 28" tire now with stock redline. Also what mph do you think i will max out at.

 

I daily drive over 90 miles a day with my TH350, 5300 stall, 4.10 spooled rear end but i also have 31" street tires.
15 city mpg and 20 highway mpg