Dr. Z offers Interactive Metronome® and has posted several testimonials from his clients. Read the comments and note how people all over are seeing the same typical gains with IM that I am seeing; reading gains, initiation, attention and focus. Gains become fairly predictable when you've seen enough people through the program. We may not know exactly how IM works, but we can tell you what it does! Check it out.
Dr. Z's Webpage