Originally Posted by turtle64b

So you have two Mass Air Flow sensors that meter the air coming into the engine as it flows past them. There is also a Manifold Air Pressure sensor on the back driver's side of the intake manifold (stock or Stillen). With the a2w setup, that heat exchanger is in the way of air entering the intake manifold and getting to the engine. This can cause pressure fluctuations (turbulence) where the stock sensor position is. Moving the sensor to before that heat exchanger (n between the TBs) gives you a more accurate reading of manifold pressure.

With the a2a, that intercooler is not in the way and so the air flows through the TBs into a giant cavern (relatively no turbulence) before entering the engine.

Just my thought on the why, but I am not an expert.