dual quad nitrous !!?!!

How many passes do you get out of a 10lb bottle and how much do you use as far as shot size and all that? And size motor? Just trying to get an idea of what I'm getting myself into...
Thank you..
150 shot on a 10lbs bottle, I used to get 3 passes in before it would start to peter out. 15lbs bottle would get me 5 passes before the same. Yes, it makes it expensive to go racing, that is one of the reasons why I stopped using it years ago. My 50$ race would turn into a 120$ race if I went rounds.