Given we don't have the full flow test including the test bore used... My take... The combination of a 300cfm head, 1.5 ratio rockers, 2.08 intake valve on the 4.03 bore, and cam with (very) limited lift are all adding up to what I see as a dip in the ability of the intake tract to properly feed the engine at WOT as the rpms climb. Valve shrouding does have an impact, especially at low lift. If the heads flow well at higher lift there's usually a sacrifice in off-the-seat and low lift ranges. Then the intake valve is opened against the cylinder wall and not far enough to really let the unshrouded areas make up for it. It's making "good power" as it sits on the dyno and not knowing anything else about the intended use or owner. Given the numbers produced for them it's probably going to be fine. In my opinion I think the heads and camshaft choices could have been a better fit in this case due to the bore size but my truck doesn't rev over 4K even when I'm using it hard so the question of "does it matter" comes into play.