You might be comparing apples to oranges here with the Carbed setup Vs a Fuel Injected setup. The length of the runners really isn't an issue here because the fuel isn't mixed at the throttle opening. This is the beauty of the injection system, a compact performance design.
Take note in the differences between the L36 and the L67. The NA needs the injectors in the manifold to help mix the fuel a little more before it enters the cylinder....The L67 pretty much mixes it as it's going into the cylinder. My perception could be off too, it's just my observation. It's kind of hard to find sources to compare why they designed things the way they did.
