Frightprops.com has a fantastic knowledge base on pneumatics, that's a good place to start.
http://www.frightprops.com/faq/category/2/pneumatics.html
http://www.frightprops.com/faq/category/2/pneumatics.html
whats that?You can use a reservoir tank to give you extra volume when needed, these are pretty cheap and can easily double the volume of air available when demand goes up.