E-street vs Promaxx vs 440 Source

I’ll add this.......
“IF” they are having the heads CNC ported......... and leaving the valve job untouched......in other words, the same as the ootb heads....... then I can see the numbers not being too far off.

I know when I messed with some bowl blending on those...... the gains were pretty small until the seats were addressed.

“IF” they flowed similar numbers on my bench to the numbers in Eric’s video....... I’d say they probably need a little attention somewhere.
Any of the Ede originals or copies........ should all be a solid 300cfm+ to justify the cost of the CNC job.