It was useful to print out sections of the Garmin installation manual for a 3-ring binder. Garmin put the pin assignment diagrams and text separate from the descriptions of mounting the units. Each section of the binder collects a short excerpt for the unit and the related terminal diagram, pin assignment table, and descriptive text. Printing out the entire Garmin manual would be a huge waste!
Once the wiring is complete, you'll probably want to print the 200 or so pages of "Configuration".