Unlike previous Zumo models, it's not officially possible to change the Splash Screen at startup on the Zumo 590 and 595. However, since different Splash Screens DO exist (eg: BMW, Harley Davidson, Touratech have different splash screens from the standard Garmin one) if we knew where these were located, perhaps it would be possible to change them.
When I updated a Harley Davidson 590 to the Garmin 595 firmware (there is no HD version of ...