How does a person with 4.56's and an AOD end up with a calibrated speedo?

[420nitro]

N/A =normally asparited ==no power adder like a turbo or super charger.
If you want a bad ass converter..look for a stall thats about 1,500-2,000 rpms below shift point. (Thats for more of a hard core strret/strip set-up)
So if you shift at lets say 6,000 rpms your going to want a 4,000 stall.
I know,I know way to much for a street car.... I run 4,800 on my street car.
If you like to play on the hwy and stuff like that, look for a 3200-3600 stall for a "4.56 geared" mustang with your engine combo. (This is where alot of people mess up and don't look into the proper converter applications.
And then you will need to do some work to your engine combo to make power in the upper rpm range so it all sings together.
And don't pay any attention to below 2500rpms.