2 hp per cfm is supposed to a reasonably attainable power level, I see most street strip fall slightly short (1.7-1.9) on this rule of thumb.
One engine I do see reach 2 hp is the 5.9l create engine dynos 400-410 hp on 200-210 cfm, 2.5 would be 500-525 hp how much cam and cr etc.. would you need to add to get there ? :)
