There is no "standard" for what a 40 day MC will do. Even for the same person each time will be totally different. I've done 10+ 40 dayers in the last 9 years and each one has been totally unique and different. As with any cleanse it's all a learning process and each one will reveal something different.
The best thing is not to make a big deal of it. Follow the intructions in the book. Don't whine. Do it with an open mind and NO expectations. Know that you are doing something great for your "health" and you'll do just fine.
What you have to also keep in mind that none of the cleanses are the goal. They are just tools that take the garbage out to allow the system to operate more efficiently and any and all "benefits" hinge on what you put back in AFTER the cleanse.