What RPM's would you be seeing these increased numbers? What RPM are you starting these pulls at? Obviously the numbers you are seeing improved are under the curve, since timing would be all in by peak HP RPM, maybe not at peak TQ RPM.
Usually on a dyno I start my pulls between 2500 and 3000...
I wouldn't lock a street car down either, but run a MPP dizzy and see what the curve is. It might as well be locked. His car is never even under any significant driving load under 3500 RPM. If it's not detonating and it isn't pushing back on the starter, where's the issue?
Don't get caught up in advertised powerbands. It's utter nonsense.
On my 440, I run a much bigger roller cam and the best standard port heads money can buy, topped with a deep ported Victor and mine peaks at 5,900.
What cop pulls your wheels off and checks your brakes on the side of the road?
I guess follow the laws if it's that strict. I'm glad I don't live in Aussieland, especially after seeing what they did to you guys since 2020.