Should gpms every exceed max rating?

Ie. 2” spa return and drain.
PB is telling me to run pentair VSF at full speed to power 8 jets.
160gpm max/ 8 jets=20gpm thru 2” pipe to a 1.5” outlet in the spa.
My understanding was max velocity for 2” is 8gpm flow, 6gpm return.
What am I missing