i am quite aware of the erick's setup.

FI doesnt at all represent flow numbers for NA applications. forced air will always flow relatively well in most applications.

as for NA, air velocity reigns supreme for creating power... bigger is not always better. considering the design of the GSR manifold compared to a single runner application, it's obvious as to why the single runner design will usually perform better by design.

the runners being short length in comparison to the long tubes on the GSR manifold are superior for top end performance. the GSR type is sufficient for most street applications as the short and long tubes combined provide for 2 different motor attitudes. but the application of the tube convergence and butterfly valves to control and divert airflow in the manifold will cause intake turbulence and resistance to flow that is only excacerbated in an NA configuration as the air isnt being forced thru the system... it's being pulled in at atmosphereic pressure.