As standard, my car got it's 2nd wind at around 3.5krpm.
The compressor just exagerates this so it pulls hardest from there on.
Regarding official figures, i think this refers to TTE having got TUV certification with a pre production version of the kit. Since then, some minor changes have been made - pipe diameter, cable rather than vacuum bypass ... not significant enough to re-'TUV' but may have improved things slightly. Mat knows more about this than I ...
Also, people have done additional mods which may contribute to better performance figures.
Morph, Mat + Gordon all fall in to that category.