speedo still off!!

here is the low down installed ford gears of the 4.30 on my 2002 gt. using stock tires and stock wheels and using the preditor hand held tuner the speedo is still off by 12-1mph!! what the f**k!! is there something i'm missing all comments are appreciated. thanks
 
The speedo is off by 12MPH (a) at what real speed and (b) which direction (fast or slow)?

If you're reading 72 at 60MPH, that's a 120% error. To me that indicates that the Predator set the gear calibration to ~3.55, not 4.30. I'd double-check your settings and what's actually been programmed into the PCM.
 
Some of the older revisions of the predator have a glitch if you use the 87 octane tune the gear change in the tune won't take. You have to use the 93 octane tune. You can update the predator to the latest revision but then you lose the ability to turn of the post cat o2's and egr.