After upgrading my extruders to flexion extruders and hotends and installing a IR bed probe to the extruder carriage (see Duetwifi conversion here: https://www.thingiverse.com/thing:2428995) I modified the excelent cooling fan mounts from 3dprintler which I did use with my old setup before to fit the new setup.
This required integrating standoffs between extruder fans and cooling shrouds as well as reducing the outlet height as the flexion hotends are a bit shorter then my old hotends.
Best print in ABS, solid with no raft or support (the file has integrated supports at the opening closest to the hotend which needs to be removed after printing).
Visit 3dprintler's thing page for info on the fans required (https://www.thingiverse.com/thing:221306).
For my installation I combined 2 fans on one of the duetwifi's PWM fan connectors and control the via the slicer depending on layer height, print speed and status (e.g. bridging) for PLA and ABS prints (has improved the ABS print details significantly).