Well, hopefully I'm not mistaken but short runner is the wedge shaped ones, long runners are like a big old log
Going purely from my thermodynamics knowledge, the short runner will provide a more even intake pressure per cylinder than the long runner. This is because as the air flows into the IM, cyl 1 will be pulling in air - a pressure drop. To overcome this the overall displacement of the IM decreases to maintain the same pressure to cyl 2. This repeats to cyl 6 where it is at its smallest. The only issues I can think of for this design are the potential turbulences as not all 6 cylinders are firing at the same time (duh!). IIRC firing order is 1-5-3-6-2-4. So you can see that air will be pulled into each cylinder not sequentially and the mass of air in the IM will be pulled back and forth.
Another advantage to the short runner style is the air intake is pointed more directly at the cylinder intake. The more direct the path, the faster the air can travel. This is a good thing
Long runnes? Well, I can forsee the same turblance problems but at a larger scale as the intake air has to turn at 90 degrees to get into the cylinder.
