Papa Juan - There IS no PAV on the C5! It runs plenty clean enough not to need that extra complexity. The airbox was left the same so as not to disturb the smooth air flow over the manifold absolute pressure sensor. As I explained in an earlier post - the volume of the stock airbox is huge to allow non-turbulent air to flow through the throttle body. This enables the MAP to "see" the most accurate air flow in the intake without reversion or other pressure pounding that a small volume airbox would create. I believe that changing the airbox and ignoring the MAP's sensitivity would lead to worse, not better performance. Opening up the "go outer", however, seems to be what the little engine REALLY likes!