Intake manifold. Copied Elddebrock performer RPM.

@YY1 I have no issues with mine. The runners are slightly different in shape and smaller in size. It’s on a 10.5-1 - 360 with a Thumper cam @ 230@050 topped with a 600 AFB and headers.

To read one above that ram 11.60 in the 1/4 is encouraging for sure.