Originally Posted by FMOS Racing

That ignores the torque multiplication generated by the lower gear.

If torque x lower gear at 7400 is greater than torque x higher gear at 5000, it'll still be accelerating faster at 7400 in the lower gear.

So, for 7000 rpm = 310 ft-lbs and 5500 rpm = 375 ft-lbs in 3.06, 1.63, and 1.0 gear ratios,
At 7000 rpm in 1st gear 3.06x310 ft-lbs = 950 ft-lbs
At 5500 rpm in 2nd gear, 1.63x375 ft-lbs = 610 ft-lbs
Still accelerating faster in 1st at 7000 than at 5500 in 2nd.
At 7000 rpm in 2nd gear, 1.63x310 ft-lbs = 505 ft-lbs
At 5500 rpm in 3rd gear, 1.0x375 ft-lbs = 375 ft-lbs
Still accelerating faster in 2nd at 7000 than at 5500 in 3rd.

Dyno didn't go high enough for me to use 7500...

I went from a 2800 single disc lockup (call it a non-lockup for all intents and purposes) to a 3300 5-disc lockup and picked up .5 and 7 mph in my tow rig. Most of that was from eliminating slip at higher RPMs, it got about .1 to the 60' mark.