The short side radius is where you get the big flow gains in head work. Valve grinding equipment doesn't touch them, and the wrong throat cut can even make them worse. All the other stuff you do in head porting is just small gains compared to getting the short side right. Knowing what to do there seperates the good head porters from all the rest. Cut too much and you ruin the head just as quick as sinking the valves. The only cure at that point is epoxy.
