I never saw any of Eric's videos until this morning. Interesting results on the 906 CNC 2.14//1.81, the 902 hand ported 2.25/1.81, the hand ported 452 (with 2.055/1.60 valves?), must have left Chevy valves on the parts list 'cause the 452 valves should be 2.08/1.74 stock.
On a 8.9:1 440 with 346 heads (2.08/1.74) and an XE285HL camshaft, every time we ported and lost flow at .100-.300 lift and gained flow at .500-.600 lift, we gained horsepower across the entire rpm range. Gotta say we never saw a 30 cfm drop. The most I recall was 7 cfm @ .300".
When all we did was install 1.81 exhaust valves in place of the 1.74 we gained peaks of 11 LB-FT and 16 HP.
Very seldom have we ever tested the MOPAR big block iron heads with stock sized valves. We usually go to right to 2.14, 2.19, 2.20 or 2.25/1.81.
We have tested a 902 head with 2.25/1.81 valves. If Eric did actually test the 902 head with 2.25/1.81 valves, that head with those valves has the potential to considerably exceed his listed flows. I think the 902 test like the 452 test may have listed the incorrect valve sizes.