in-line fuel pump?

[gunmetal]

My friend seems to think that a in-line fuel pump wont help if your pump in the tank isnt a fast/strong as the inline pump so there fore the inline pump would be a waste. it does kinda make sence, but doesnt the inline pump help pull it out of the tank through suction? just wondering becuase if the in-line pump thing does work i wont have to drop my tank and all that bull. plus i like proving my friends wrong. Thanks for the help,