Installed 2 in series in my Scooter today and my first impression is WOW! Cfm's are impressive for series and believe it or not there is an increase in cfm's when both are on (the 225-250 cfm now seems very probable after using them). Lift is 13" Hg at the machine and 12.5 Hg at 50' of 2". I have 8 portable jobs scheduled this coming week, so I will get some time on them, but I already know that they kickass! My small footprint Scooter is now on par with an Escape in the vacuum department.