The autos come with 3.15's because of the steep gears in the transmission. If you were to do the math it would come out to a 3.55-3.60 gear. Many have done gear changes with no improvement in their times. The fastest N/A autos are running 3.15-3.31 gears. The autos tend to feel a little sluggish off the line because they need two things. A good tune and a converter. The converter makes a significant difference.
Last edited by scottmach; 03-28-2014 at 01:07 PM.