I wonder how much the 3:31's would affect fuel economy?
When I went from 3:23's to 4:56's in my Dart, the MPG's took a real nose dive!
the only real hit will be on the hwy at cruising speed where at a give speed your rpm will be 15-20% higher. In town it'll be easier to get it going and if wanted you can be in a higher gear. I drove both and the 3.31 (or higher) is the way to go. Bad news to make the odo/speedo work properly you need to get a tune or have the dealer reflash for the gear ratio. Ford only supports up to the 3.31 in the V6.