<p>I personally used the Barron's books for the AP tests and some of the questions i saw on there(especially for APUSH) turned out to be the exact ones that appeared on the AP exam.
But i do feel like Barron's SAT II math IIC is a bit too hard from things i've heard about the real test.</p>
<p>Well, Barron's SAT II Math IIc book is absurdly harder than it needs to be.
On the diagnostic test I got "Above average" and on the real test I got 800.
That diagnostic test was the only preparation I did before the test.</p>