This started off as just something that I thought would look cool and so I could practice making nice curved shapes, but it actually provides a small benefit. Since the nozzle reduces in diameter, it accelerates the airflow. Smoothing out the shape of the center fan area seems to reduce drag as well. The real benefit seems to be that it's quieter. It's really meant for the reversed fan mod.You will need slightly longer M3 screws (45mm) to accommodate the extra length. Try and print without raft or supports.