What really limits our engines to rev higher

[Aevus]

The Drag Pack cars made 800hp with unported gen 4 heads.

Unported gen 4 heads with 2.08'' valve = 312 CFM @ 0.500'' lift and 327 CFM @ 0.600'' lift (passed that it drops)

it's not that far from the numbers I have with my ported gen 3 heads and I kept the 2.02'' valve diameter (for few reasons) so I think my target of 750 crank HP is reasonnable


Edit: Sorry I think the numbers here are with stock valves and the ported one with 2.08'':
http://www.speedstore.ca/VP4_flow_sheet.html