When GOOD 440-1's can now flow 380-400cfm (400cfm with the 2.30 valve) Whats the point of the 572-13 heads? And if you want mid 400CFM flows you just go B1 Mc's or the PSO's. and if you want 500++ Well you go Predator or B1-TS.

440-1's are the best heads out there until you want over 400cfm then B1 takes over IMO