[Aussie Mike]

You cant really compare rear end ratios between a T5 and T56. The T5 runs a 3.35:1 Ratio first gear where the T56 runs a much taller 2.66:1 ratio first gear. The spread of ratios from 1st to 5th in the T56 is actually closer than the spread from 1st to 4th in a T5. This means you can use much shorter ratio rear end gears and still have a usable 1st gear with a T56

3.7:1 and 3.9:1 work fin with the T56 boxes for daily driver duties.

Common T5 ratios
1st-3.35:1 2nd-1.93:1 3rd-1.29:1 4th-1.00:1 5th-0.68:1

Common T56 ratios
1st-2.66:1 2nd-1.78:1 3rd-1.30:1 4th-1.00:1 5th-0.74:1 6th-0.50:1

Cheers