I've read many threads re: the "real score" one can expect to get after preparing with these three...any other takers on advice? Some individuals have mentioned that the "real score" one can expect to get is 10-20 pts higher than the GMAT Prep, and 30-50 pts higher than the Manhattan GMAT / Kaplan...

I've gotten a max of 660 on the Manhattan GMAT, 640 on Kaplan, and 690 on GMAT Prep...

In addition, if this claim is true, any advice on pushing for the final 50-100 pts? I'm doing problems, problems, problems...mainly from the Quant and Verbal official guide, and trying time myself as well. Any other strategies to push through the last leg would be very useful....

Thanks.