In most cases in vue percentages can go above 100% :) Even if the slider wont go above 100% you can type in a larger number in the numeric field and it will indeed have the appropriate effect. I havnt tried it for star densities but I'm pretty sure if you type in 1000 you'll get ten times as many stars.

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/