Gears don't increase the torque of the engine, but they increase the drive force at the wheels. Like in the bike analogy, in first gear your legs aren't exerting any more torque to the pedals, but there is more force applied between the wheels and ground, then there would be in 2nd gear.
3.73s seem to be the choice for GTs. To make them even more effective consider buying a shifter also. It makes for a really nice combination.
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'97 Cobra, K&N, Flowmaster, subframes, 4.10 gears, Steeda Tri-Ax shifter, Steeda G-Trac 3, Cobra R wheels w/ Goodyear F1s
My Ride