I read the flow info they had on thier site.I have many many many hours on a supperflow flow bench. yes you can make one your self out of a shop vac like they did.but what I read did not seem to make sense to me. more like they were restricting the flow from thier readings & what they said. a higher vac is usualy a lower flow,I know it dosent sound like it but thats sort of the way it works,you realy need to know the whole prosess.with all the settings the same a good flowing head will have a lower reading than a restricktive head& will need to be checked at a defrent flow rate. just because it making more noise dosent mean it's faster.Might just be the way I am reading it or the way they are wrighting it. sounds good to someone who hasent spent 20+ years on a flow bench doing cyl heads,carbs, stacks,etc. but dont to someone who has. put it on a dyno for back to back runs.no not a but dyno. or a drag strip with a car& driver that is consistant. I am not trying to say it's wrong or wright I don't know either way. sort of like if you hold up a quater 1 foot from your face then hold up another Quarter 2 feet from your face ,witch one is bigger???? think about it.............................. there both the same size!!! reguardless of what you think you see.