http://www.javacertificationexams.com/scjp-mock-exams.php for free mock
test I haven't buy whizlab so i have no idea about it but people in forum say it is more than enough
I have read kathy sierra book
I had given mock test from black belt ->other programmers exam it contain five mock test,jdiscuss, green, cafe4java and javanet for generics
javanet contain very tough question for generic
But question for generics which I got very simple even simpler than self test answer in kathy sierra book
Read kathy sierra book very carefully(or atleast two minute drill)
learn all the exam point and practice all the question from self-test answer(why this answer is wrong or what happen if this keyword is not present in question it will help you to understand your concept more )
The most important things is your presence of mind in exam read the question in exam very carefully
Thanks for helping me to achieve that good score