After a failed dual extrusion print that required the removal of both hot ends for cleaning I decided to leave the left one off since it was the only thing stopping me from using a true annular cooling duct. This works really well providing airflow from 360 degrees. I am using the Flexion extruder/hot end setup on a Wanhao Duplicator 4X, but I don't see why this wouldn't work with a stock printer but I did not try it.