At some point in the future I will get one of the GM cores (they seem to  have become the de facto standard) and run a side by side test.  I  envision a simple, go/no-go test consisting of a pump running water  through a hose to the radiator laid flat on a table.  From the radiator  a hose will run out to a 5 gallon bucket.  The highest flow will fill  the bucket the fastest.  Completely unscientific and it won't say if the  Altima radiator will flow enough, but it will be quick and easy.
 --  ----Because I can----
 http://home.nc.rr.com/deltabuilder