Direct Connection ( Mullen LA ) heads

How are you determining that the flow range is 344cfm.....@10”?

344cfm...... @10”............. is 575cfm@28”.

If you aren’t applying any kind of correction to go from 10” to 28”....... then I agree with YR in that your numbers don’t agree with......pretty much the rest of the world.
296...... @10”...... is 494.9cfm@28”...... and I’m pretty confident in saying those heads don’t flow that.

Sounds like maybe you could use a few PTS test plates.

.
100=52 52%=.178.8

I’m not sure what size valves are in those heads, but even if it’s a 2.08”....... [email protected] lift is 188% DC.l(if you assume that’s at 28”)....... in other words...... not possible.
But, you’re saying that’s the observed flow @10”, which would be
298.9cfm@28”, at .100 lift..... which is 316% of what’s possible.