To upgrade from the V3 extruder to the V4 extruder, simply purchase your V4 Rev F/G Cooling Upgrade and follow the instructions provided by the assembly guide, listed in the link below:
Download Assembly Guide - V4 Rev F/G Cooling Upgrade
(Before September 2022):
Download The Old Assembly Guide - V4 Rev F/G Cooling Upgrade
You must print the junction box which helps with wire management ( "Metal Motor Mount Shroud . . ." ). Instructions for upgrading from V3b and V4