I took kaplan and although the course did help, two books that I bought, AP cliff notes o chem I and II, were a little more effective. I was scoring 17's on my kaplan diag's and after I started studying with those books, I got a 20 on the O chem portion on that Kaplan DAT final diagnostic (I was damn proud of that). Strange thing occurred on the actual DAT though. Most people reported an increase in score from the practice, supplementary tests to the actual exam. Not me. My score dropped and I actually got a 17...f'n DAT. Hopefully, that doesn't happen to you! Good luck brotha!