There is a great deal of variation in student improvement. For one thing, your improvement depends a great deal upon why you got the initial score that you did. If you ran out of time at the end, you may see a significant jump just from learning to finish on time. Also, have you studied at all, or are you brand new to the test? Are you comfortable with English grammar, with reading passages in different subject areas, etc.? How about math? Did you miss problems because of small errors that can easily be controlled for, or did you consistently find the problems difficult to understand or manipulate?
I often see students improve by much more than 100 points, but it takes a lot of hard work. You have to be very consistent at looking at what you're doing that is and isn't working and then targeting your practice to build on your strengths and address your weaknesses.
Good luck!