I found this on page 90 in Leo's book describing a "Econoflow" head that Sissle marketed using stock size valves.
"The head bolt boss in the middle of the intake ports should be shaped like a wing, but left in place. Removing the boss will gain about 5 CFM on a stock valve size head, but the subsequent loss of velocity in the port will more than offset the gain."
This supports the the idea that removing the boss and adding lumps doesn't help without an increase in valve size. It may even hurt because of loss in velocity.
What we are trying to do with our truck engines seems to be kind of unique here. We are trying to make them a little better at what they were designed to do while others are trying to turn them into higher RPM hot street and race car engines. In some ways our job may be harder because they were very good at what they were designed to do.
What we want is over by the time data shows on Tom's dyno tests. By looking at the graphs it is clear that serious torque gains were made by the big valve head with the big cam both with and without lumps, good torque was produced across the RPM range tested, and the torque was already there at the beginning of the graphs 2.500 RPM.
What we don't see is what a cam designed to build torque and fuel economy would do from idle to 2,000 RPM with a stock valve head prepared like the Sissle "Econoflow" described above. For me any improvements here are the goal and it is cheap, basically stock valve train.
