I was thinking similar, but even still though the popular LS 706 is topping 230 cfm @ .700 getting 2 -2.4 hp per cfm with what most would consider fairly mild cams for the output.
Magnums are know to respond well to cams and don't flow that much worse, seems to make like a 100 hp less with similar cams on a 5.9l.
I imagine the ports are efficient but that seems super efficient.
But I do notice there exhaust ports flows really well was thinking that had a bunch to do with it too.
