Alternator Sizing - Amp requirements

I actually called and spoke with a lead engineer at Denso when I got their data sheet. One thing I thought was interesting was that he mentioned that they rate their alternators very conservatively. The two data sheets that I've posted are essentially for the same alternator - only one's from the manufacturer and one is from a rebuilder. I guess it just shows the numbers in the test are simply a function of the parameters they are tested under. Kinda like flow benches and engine dynos...