How much hose can you run from a given blower?
The question (and answers given so far) seems to assume that all blowers of a given size perform the same regardless of how fast they're turning, how much the inlets are choked- down and how much the exhaust restriction they encounter.
It's not that way at all.
Assuming that a 45 / 4M / 4005 is running at highest- rated RPM, there's no inlet restriction (i.e., no bushings in the blower port restricting the diameter there, etc.) and no restriction on the exhaust (i.e., silencer is sized correctly and not full of corrosion... exhaust isn't being forced through an exchanger, etc.), you can routinely run 500 feet of 2" hose and be satisfied with the performance.