If you're only missing 3-4 in 37 minutes, seems like a good start to me.
I dont know about others but i can say that you have improved. Going down from 80 min to 37 min is an achievement though not something that you would be aiming for. Also you are getting 21-22 ques. right which is pretty decent. You just need to work on the time and try to eliminate the wrong answer choices within 20 seconds.It would be good if you bought one of those silent timers. I personally bought the $30 silent timer from silentimer.com and i love it. The good thing about it is that it even tells you about time limits for every question after you put in the # of questions and time limit. Dont worry you will improve.
I'm confused, are you using the book as you do the questions?