Now I know this may seem a little bit strange to some people but why are people quoting flow rates in lbs/min from a compressor?
It will flow a fixed volume at a fixed speed so unless you quote what air pressure and temperature you are talking about then the figures are useless as a comparison really.
As an example, say that my turbo actually flows a maximum of 500 cubic feet per minute.
at 20°C and atmospheric pressure, the density of air is around 0.0745 lbs/ft³ therefore the turbo will flow 37.25 lb/min
Now say I decide that rather than measuring the flow at 20°C I measure it at 5°C........ the density of air at 5°C is around 0.0788 lbs/ft³ and so by some miracle

all of a sudden my 37.25 lb/min turbo can now flow 39.4 lb/min
So unless you know the actual test conditions, quoting flows in lb/min doesn't really tell you anything about how much of an improvement you may actually get from fitting the turbo.
Andy