That chart gives you a pretty good idea of what you should see for flow with a .6mm jet. Unfortunately the reality is that the espresso machine jets that I've played with in my Speedster over the past 7 years are not accurately sized. The greatest variations I've seen are with the brass jets. One ".6mm" jet might flow 450ml per minute & the next 600ml per minute. The ".6mm" stainless jets I now use are much better but the flow rate is still higher then what that chart shows running in the 550ml - 580ml per minute range. These flow rates are with a real time group pressure of 8.75 bar. The gauge reads about 1 bar higher. If you have to go down to 6 bar to get into 500ml - 525ml per minute range you can bet that your LM .6mm jet is actually much larger then the stated size.

LaMini wrote:I adjusted the brew pressure to 6.5 Bar to get 250ml per 30 seconds and the shots are steady, rich, creamy and yes with a lot of crema. I know that when I get the Monolith probably I will need to change things a little bit. Will see...

And the shots weren't "steady, rich, creamy & loaded with crema at 9 bar with the .6mm jet or was there some other reason to drop the group pressure to 6 bar?