Team 3238 is having the same problem. Precharging cylinders definitely make a big difference.
We just toyed with the idea of having elastic-assisted pneumatics, but when we hooked up the festo valve to vent/reverse drive our cylinder, it actuated
very slowly.
Any ideas on why this is/how to fix it? opinions on elastic assist?
Also, if anyone is also looking for a good vacuum mechanism, this may help:
http://www.chiefdelphi.com/media/photos/34700