I have been meaning to try out the custom firmware ADVi3pp for the Wanhao Duplicator i3 Plus, and it's many clones, such as the Monoprice MakerSelect Plus, Cocoon Create, Powerspec i3 etc., for a while now. I plan on installing BLTouch sensors in both my printers soon, and this firmware is a requirement to make that work, so I wanted to get a bit of experience with it first.
We go through the flashing process and have a look at it's features, as well as do a test print. I used some variant of version 3 for this, version 4 has additional features, that might simplify the process, especially if you are adding an auto leveling sensor.
ADVi3pp Firmware: https://github.com/andrivet/ADVi3pp-Marlin
User manual: https://github.com/andrivet/ADVi3pp-User-Manual