ECeptor

Are the 360 number for a ported head? It kinda hard to tell for sure because of how the test wraps, but looking at some of the heads below it looks like it's ported by BHPerformance Iron.

fbh-velocity

You are right, it could look like itīs a ported head, but if you compare with 049 head with standard valve they are very close. And as far I remember it was 049 heads they used until early eighties
Another factor is that the DTDyno are automotive exhaust choices. This could vary to marine exhaust system because i think auto mufflers, 2 or 3 in line, are more restrictive than marine thru prop. The only compare able exhaust system is header without muffler and marine header thru transom.

But no matter what, its much essayer to make 330 DTDyno hp out A the newer gen6 with roller cam.

Its hard to believe that the marine industry would sell fake horsepower