Hi zura,

In my experience, most CAT practice tests from the reputable GMAT companies give relatively accurate results (maybe not exact, but not off by 15). Of course, this varies based on the student. Sometimes, the pressure of the test, the perceived need to rush things, and even a poor mix of questions can lower your score on the real exam vs. your practice tests.

So, my advice is to focus on improving your comfort level in verbal, rather than looking for "more accurate" practice exams, so that - next time - you won't be surprised on the real thing! (Of course, it's still great to do more practice tests, but I think the more important issue here is improving overall verbal performance).

Good luck!