anyone ever flow test 383 A body manifolds say vs 383-440 hp manifolds

As bad as the ex manifolds are, on what I’ll call the “higher effort”(but def not max effort) FAST legal type builds, the factory iron square flange intakes are also quite poor for making big hp.

I dynoed a nice little 511” low deck FAST build one day, and a 499” 6bbl build the next day.
Both were very close to 12:1CR.
Same exhaust manifolds and 2.5” pipes used for both.
Same solid roller cam in both, 906’s on both, and the 511 heads were a few cfm better.

The 6bbl combo made about 65hp more than the 4bbl combo.

At a FAST event, the 511 went 11.58@117 at 3670lbs, thru the ex manifolds and 2.5” exhaust system, on G70-14 repro redline bias plies.