Hi vinus,
GMAC has publicly stated that the Official Score that you earn on Test Day is within +/- 30 points of actual ability. Given the 'swings' in the Scaled Scores on your practice CATs (and Official GMAT), I have a few questions about how you took your CATs:
1) On what dates did you take each of these CATs and the Official GMAT?
2) Did you take the ENTIRE CAT each time (including the Essay and IR sections)?
3) Did you take the CATs at home?
4) Did you take the CATs at the same time of day as when you took your Official GMAT?
5) Did you ever do ANYTHING during your CATs that you couldn't do on Test Day (pause the CAT, skip sections, take longer breaks, etc.)?
6) Did you ever take a CAT more than once? Had you seen any of the questions BEFORE (re: in an online forum or in a practice set)?
GMAT assassins aren't born, they're made,
Rich