a working PIWIS setup, noting the PIWIS version and model year have a strong relationship
a suitable ODB2 scanner, either TabScan T6PT3G (newer, more $) or VAS6154 clone (older, less $)
a 100A power supply (not charger) especially if you're going to spend more than 5 mins 'playing'
patience along with a relatively high risk appetite
If you need to get started building a PIWIS system, this guide is a good place to begin
Power/Torque display on non-GT3
Traffic Sign Detection
Gear shift assist on non-GT3
InnoDrive
LKA
Expert Menu
Night View Assist