I get what your saying and agree with the premise but when you look at builds of certain levels cam, cr, etc.. and look at the hp and head flow the hp per cfm is generally in close range of one another somethimes you'll see one that surprises you. When you hear Darin Morgan talk about hp per cfm I hear him generally give is 2.4-2.5 hp per cfm causes that's the world he lives in. Most street/strip engines don't seem to make even 2 hp per cfm from what I've notice they seem to fall in the 1.7-1.9 hp per cfm, does that mean your guaranteed to make that no but generally you should be able with the right build some may need a little more help then others. And yes an engine that makes 1.7 vs 1.9 or more can be a huge power difference I'm just saying there is a general correlation between cfm and hp or we wouldn't use it at all.