Thats right, smaller ports make great low rpm torque! Big ports move a bunch of air at high rpm. You want high volocity at low rpm so the air actually overfills the cylinder. If you can move it fast enough, it will keep filling the cylinder even though the piston has stoped pulling in air.
In my case, we filled the ports with epoxy to redirect the air flow. If you look at a 250/292 head and compare the port floor to any decent V-8 head, you will see the differnce right off. There is no short turn in the 6 head. A "short turn" is a name for the turn the air makes from the floor of the port to the valve head. Air likes to follow a certain degree of turn. If the turn is to sharp, it will jump off and bounce around the valve stem or back wall of the port. By raising the port floor, I was able to blend a nice smooth turn in to the valve. Take a propane torch and blow fire thru the port, you will see how air flows thru the head. On a proper radius, the fire will follow it right around the corner, if its wrong, it will shear off.
Again, in my case, we closed off 1/3 or more of the port but still retained the same air flow up to .300" valve lift and from there to .500" lift it picked up air flow. So we got more air through a smaller port with out any major cutting or machine work. That will always make it run better. The lumps they install do the same thing, make the ports smaller and redirect the air up and over to a good turn in to the valve. They cut the divider out for easy placement of the lumps, not for a increase of air flow. The added flow is a by product of the lump mounting procedure.
In the racing manual, you will see the total port volume of a full race head is smaller than a stock head. Port volume is total area in the port. If you shut the valve and filled the port full of water up to the intake flange, the race head had 225 cc's and a stock head has 237 cc's. Yet the race head flows 264 cfm compared to a stock head of 169. Mine in stock form flowed 168.5 and modified was 191 cfm.
Joe
