Rich - it's not simple maths at all. Go and include restrictors & flow, then try again.
Steve/Paul, whoever is using the account. I'm not telling half the story @ all.
djr has already made mention of restrictors and so on. Also assuming drains are enlarged as well and no need for silly external drains that are the latest "fad" that everyone seems to need - but never has before strangely enough.
There are more cars here running N1 pumps in circuit cars than there are Tomei/Jun etc. I guess everyone is a fool... But all are reliable fools, so proof is always in the pudding. I go on results and hard evidence, not hearsay or people unwilling to admit they broke their pumps to due abuse or tune.