I know just enough to understand that putting in a steeper set of gears is one of the most bang for the buck upgrades there is. Are there any cons to doing this? I mean I know that it will give quicker acceleration, and thus quicker ricer kills, but are there any downsides? There's no such thing as a free lunch. For example, is there a loss in "drive-ability", gain in vibration, noise, or loss of gas milaege? (Who am I kidding, we drive Mustangs, we're really not concerned with gas mileage anyway!) Is there a better gear for autos vs manuals, highly tuned cars vs near stock cars, s/c vs n/a? I'd like to put in a set of 3.73's regardless, but I'd just like an idea of what issues I might end up with.