It's a common misconception that #Gaggia's original spring lever #espresso machine design - the one that introduced modern day high pressure espresso brews with proper crema in 1947 - was a 9BAR machine.

It was not. It was a peak 7BAR machine (but more rated for 6.5BAR)

Experimentation between 1947 and 1955 by Gaggia, #Pavoni, #Faema, #Cimbali, and others pushed the springs to higher compression rates, bringing espresso up to around 9BAR.

The E61, with its rotary pump, was 9BAR ex.factory.