Other than Official SAT Practice book, where can one find the most realistic practice questions?

I currently have the Official SAT Book with the 8 practice tests and the Premium Princeton Review “Cracking the SAT” with 7 practice tests. Right now, I have taken two of the official tests and have been using the PR book simply for learning content, but have not tried any of its tests. I really don’t want to waste the Official Tests now, so I was thinking of switching over to the PR book for my next practice tests, however I’ve been reading that they are different/easier than the real SAT questions, and are therefore no good. What resource provides the best SAT practice other than the official book?

On a different note (probably one that belongs in a different thread), I got a 1390 (M-650 CRW-740) a couple months ago on my first SAT practice test ever (Practice test #2 in the official book). I then read through all the PR content for reading and writing (but did no practice questions) and simply took time to review/learn all the math concepts (I did no SAT style practice questions). Today I got a 1500 (M-730 CRW-770) on Practice test #1 in the official book. How much do you think I can improve, considering the only SAT style question practice I’ve done have been from these two tests? FYI I am a rising Junior.