My first set of Eddy RPM flowed 288 CFM at .600 on the intake on one head and 286 on another intake port on the other head on a Super Flow 600 bench at 28. inches of water. I sent them to Jeff at Modern Cylinder heads for his CNC port job, they flowed 317 at .600 on his bench and 310 on the same Super Flow bench as before. I'm sure those heads made close to 60 HP more on the motor, I ended up swapping the old rocker arms out, Chinese brand 1.6 ratio CAT aluminum roller rockers with 1.52 actual ratio to a set of Harland Sharp full roller rockers that are 1.6 ratio advertised ratio that are 1.65 actual ratio at the retainers My Duster picked up right at 4 MPH(124.5 to 128.6) and close to .25 ET (10.69 to 10.43)in the 1/4 mile with the new heads and rockers I built a bracket 470 C.I. 440 motor for a customer and freind four years ago that had a set of B1-BS heads that I had Jeff at MCH CNC port to M.W. size, they flowed 350 CFM at .600 and a little more at .700 and .800. That motor had right at 12.8 to 1 compression ratio and made 720 HP at 7000 RPM with a used M.W. port sizes sheet metal tunnel ram with two Holley 750 D.P. carbs on it The cam was a custom grind Crane solid rolleer that had symetrical lobes, 273 at .050 and .430 lobe lifts, gold Crane 1.5 extruded aluminum rockers with roller tips.IHTHs