E3D dual head on Velleman VERTEX K8400 Air Intake

I recently discovered a problem with my E3D dual head mount for Vertex K8400 http://www.thingiverse.com/thing:1687914
The fan I used generates such a strong airflow that the hot end is not able to heat above 223 degrees. This makes it impossible to print with ABS.

One of the solutions would be to replace 12.5 Ohms resistor, but I decided to take a different approach and design a duct with removable inserts changing airflow. The duct replaces insert.stl file of the original design.

air_flo