We started Ellie off at 60%, and she tolerated it so well that I've been increasing it over the past two months. I set a multi-step program that ranges from 80% to 100%, with the majority of her 40 minute session being at 90%. The Respirtech trainer mentioned the same thing about higher pressures being more effective, but also that some children (and even adults) could not tolerate higher pressures. It really doesn't seem to bother Ellie in the slightest (she LOVES her vest treatments, I think because the vest = TV time!), so that's why I've increased her settings. I absolutely love the vest too, by the way! I was so excited the day I put it on my older daughter (without CF) and she coughed like crazy. She had been sick with a phlegmy cough and wanted to give it a try, and she coughed the whole time it was on her! Ellie has never coughed, with manual CPT or the vest, so I took this as a good sign.