It would be interesting to test how much influence the pinch has on something where increasing it yielded basically no flow increase.
Like a moderately ported TA head……ported to the mid-260’s, and installed on a stout enough stroker to be sure it would exceed 2hp/cfm.
Heads like that will still have a separation problem at the SSR that increasing the pinch won’t solve, but increasing the pinch will slow the air down
……… at the pinch.
Dyno Test A would be with the pinch done in a pretty conservative manner.
Then pull the heads and open the pinch up to nearly the limits of the casting, reinstall, retest for B.
I don’t care enough to actually do it, but I think it would be interesting.