Next, we enlarged the intake runner. Port flow was up in the mid to higher lift ranges. Keep in mind your application when contemplating runner mods. Enlarging the runner becomes more relevant the higher the intended rpm range. For moderate dual-purpose applications with mild cams (230 degrees or less, to put a number on it), the as-cast runner size can be retained, or some clearancing at the pushrod pinch employed if you're ambitious. Getting into big cams (260 degrees at .050 or more), 440s can use all the area you can find, and even more so with big-inch strokers. The as-cast MP heads are actually slightly larger in runner cross-section than some popular competitive heads. We were leaning towards the large side of the scale in our intended usage.