If you notice a little improvement that's a good start. Any change or improvement you notice shows that the tape is working for you!
What are you doing before you listen? Remember, you need to study effectively before you listen to the tape. In other words, you should not just skim through a book and then listen to the tape, hoping you'll remember what you got out of the book, because you may not have gotten much out of the book in the first place.
When do you listen to the tape? When you have finished studying, listen to the tape before going to bed or the morning before a test. Make sure that when you read you are in a relaxed, yet alert state, ideal for learning and comprehension. The Personal Genius paraliminal tape can guide you into this state. Then, use the Memory Supercharger for accessing your greater memory bank, and without the common urgency people experience when they're taking a test. Personal Genius is for input, and Memory Supercharger is for accessing the input.
Good luck!