A common thought of high performance builders is that the larger runner volume of the siamesed intakes actually helps boost performance and that separating the runners is the wrong thing to do. Since adjacent cylinders pull on the siamesed port at different times, some racers run only 3 larger injectors instead of 6 smaller ones. The Sissel racing head design makes significant efforts to blend the two ports as well and combine intake runners to increase volume and shape for better flow to the valve seat area.
