Panic, You have it right, the heat plate is bolted over the heat riser opening and the tubes from the front and rear header attaches to it. The pulses from the cylinders firing causes the hot exhaust to alternate back and forth heating the intake. As far as the pulses cancelling out at higher speed, that would seem like a plus to me. I wonder if Fenton engineered that or it was just a coincidence. NICSON headers used the same system. The FENTON heat riser manifold just has an open passage on the rear header.
Tim
