actual vs config manager weights.

As seen often in many commercial aircraft config managers, the numbers do not match what is supposed to be active. Until recently, I have always used the config manager as a reference for weights. Now that I have read the 747 manual, I am inspired to make more flights by the numbers.I can see that the config manager for the 737-700 quotes a MTOW of 153,500LB, while all the charts in PMDG's manuals quote a maximum of 133,000LB. As a result, ZFW/MFW/MZFW are affected. Thus far, I have been flying quite successfully on the manager's numbers, rather than what the aircraft should be flying with. That could explain why I am finding rotation speeds at the level of the heavy boeings!!!!