Boris, Thanks for sharing great news with us!
4 combinations is a little too much. Your improvement also inspires. Obviously you used other materials besides the math forum
do you mind telling what exactly was your choice?
Sure, the math forum
was not the only place:) However, as for an advance preparation it was the best place with the best questions. I would say that 60% of the questions are far above the GMAT level of difficulty but when you get used to the hard questions it is so much easier not to panic on the test day when you see something difficult.
About books: OG is defiantly the best, I went through it 3 times, and every time was studying something new Kaplan
is a good book with perfect 4 tests on CD. These test are CAT test and every time you improve your math/verbal level, you see increasingly advanced questions. Princeton Review
is not so bad but I personally do not like it.
To tell you the truth, during 6 month of preparations and 3 attempts to beat GMAT, I probably have read all GMAT books in Barnes&Nobels. Kaplan
Math Workout was very helpful, all other books just a source of questions for your preparation.