Check out this blog: AKU Test Preparation
The above article almost says it all that I had in my mind for a blog related to the AKU test.
You need to achieve a relatively low percentage to qualify for the interview, so in my opinion studying a different system's book or going through new concepts in SAT II books would just be a waste of time. Instead, I would recommend you guys to focus on the A'levels syllabus and to make sure that you have sound concepts. Once you are sure of your concepts, then you may go through other stuff.
If you want to polish your English and Mathematics skills, then check out the SAT I book.
My personal experience:
Back in 2012, I appeared for the test on the 8th of April, a mere month before my A'level finals. Hence, I had very less time to prepare solely for AKU test, yet I dedicated about 10 days to it. My A'levels concepts were already pretty sound so I began my extra preparation with a book called "Dogar AKU MCAT" which was just a summarized version of the Intermediate syllabus. Let me tell you that going through it was pretty useless as the concepts were stated pretty bluntly and since I had no time to practice questions based on the new concepts, and so I was still not able to answer the questions related to intermediate syllabus in the final exam. I also went through the SAT II books once which helped me understand some new concepts that were prevalent throughout the AKU test but reminding you guys again that only knowing the A'levels syllabus is enough to make it to the interview. In the last 2 days before the test, I revised my A'levels concepts.
As for the test itself, I had a very poor Physics section as most of the questions asked were from the Intermediate syllabus that I had little knowledge about. For other sections, there were more questions from the common syllabus which helped me score well. As for science reasoning, it is definitely solvable for us, A'levels students, as the concepts are tested in a very interesting way along with some general knowledge stuff.
When I arrived at the Mathematics section, I was left with very less time, and it was a hassle completing the paper in time. So make sure guys that you keep checking the clock so that you don't run out of time.
In the English section, I made a mess of my essays because of the limited space that was provided to write. They provide you with a set number of lines for each essay and you have to complete your prose within that space and my huge handwriting didn't really help in this case.
Despite all the problems I faced during the paper, I was still able to easily make it through (76%) to the interview which I have already discussed in a previous post. What I want to tell you guys is that the AKU test is pretty easy to clear if you have sound concepts and not knowing a few questions that are out of your system's syllabus doesn't makes a difference as you can easily make it through by just solving the questions that you can answer. So just perfect your syllabus' concepts before you touch anything else. Best of luck from my side.