383/t56 mileage
 

What kind of gas mileage do you think I would get with 383 (approx 400hp) and a T56, I have 3.55 gears right now but I will probably swap then out for something like a 3.90 or 4.10 later

My 383 is about the same hp but I run 3.73 gears with 5 speed tranny ( .67 fifth ). Anyway, I am about 19 mpg highway ( 65 - 70 mph).