Alright people what part of him saying "Please don't tell me to get 4.10's" don't you understand? To answer your direct question though, the 3.73's are the gear you want. I opted for them over the 3.55's and yes even the holy 4.10's. The drivability of the car goes up and it becomes alot more fun to drive. It isn't a "drastic" change, but you will have to learn the gears. As far as the speedo, you will have to get either the Speedcal or a custom burned chip.
here's one for u. i ordered 3.73's, but when they came, i opened them up & damned if they hadn't sent 4.10's. i was so anxious to have gears put in, i accepted this as a fate intervention & had them installed. love them. so glad i did not send them back. sorry, but i just had to jump on the pile with my 4.10 brothers. get what u want, it's your baby.
Swapping 3.27s for 3.55s is like going to a nice restaurant and paying $50 for a hamburger and fries when you could have gotten lobster and steak for the exact same price.
I found that just driving around normally (not getting on it) with the stock 3.27s, the engine would lug with each upshift. After reading thru tons of reviews and threads of 3.73 vs 4.10s and driving around at what the RPMs for each would be in different gears, and for the way I drive, I chose the 3.73s. I noticed a huge difference. The engine doesnt lug with each upshift now, and the car actually feels much smoother when moderately accelerating. Even passengers noticed how much smoother the car was. I think anything less than 3.73s would feel too close to the stock 3.27s. You'd still have that lugging between shifts. People who said that these cars should have come stock with 3.73s are right...I think if they had, Ford would have sold twice as many GTs. It's almost as if the car feels *natural* with the 3.73s. And the 4.10s would have been a good option for those who always want to get on it and wind it out all the time.