intake length tuning

i just was playing with a prb intake manifold and different length of intakes and how they affect
to the overall flow.
the bellmouth is essential to gain flow, without the belllmouth the flow decreases by 20-25CFM.
.

here are the results

just with the bellmouth next to the intake  321CFM

with a 66mm length pipe   313 CFM

with a 235mm pipe  304CFM

with 475mm length pipe 297CFM

the length f the pipes were exaggerated just to show how the length and affects airflow. larger cross sectional area to travel, more loses of flow.