4.10's in my '07 GT automatic (had 4.30's in my '03 Mach 1). Absolutely love the 4.10's, and the big stall converter is equally impressive in the automatic GT's (mine flashes to 4,300 rpm's and launches as hard - or harder - than a stick shift car).
Just ordered a supercharger last week for my car. With no need for the low end grunt of a roots or twin screw (since my stall converter flashes so high), I opted for a centrifugal blower to take advantage of the higher rpm's I run at WOT (Vortech V-2 SQ S-trim 8.5 psi).
Had I done a roots or twin screw blower as my first mod, I would have kept the 3.31 gears, or maybe 3.55's at the most as those style of blowers make plenty of low speed torque making steep gears redundant.
For a naturally aspirated GT, though, 4.10's are perfect. I've rarely ever heard someone install 4.10's and wonder if 3.73's would have better, but I've heard plenty of people install 3.73's, only to wonder if 4.10's would have been better. Get 4.10's and you will not regret it for any reason.