Zuberman your idea concerning flow diagonally across the intercooler with a inlet on top and an outlet on bottom is somewhat incorrect. Your assumption is based more on flow across a vessel with low or little restriction. Intercoolers actually have high resistance to flow under high pressure. Each bar of the intercooler can flow only so much CFM, as each bar meets its top flow rate the load will be divided across each bar within the intercooler. It will not be completely proportional but will be sufficient for what we need. If your really concerned about flow then you can calculate the k-factor, flow rates, and heat transfer just like the Nissan engineers did. I noticed that you recently damaged your intercooler and may have lead to this discussion. If you have the ability to upgrade I would like to suggest Ash spec massives along with his 2.5 piping, it would be a large increase in flow and efficiency over stock.