At this moment good and detailed GPS hiking maps of many Italian national parks can be found on the website of digitalwalkingmaps.
Of course ...., these maps are not for free, good maps cann't be made if nobody buys them.
And on the website of Digitalwalkingmaps.eu there is a lot of inside information about the Garmin mapsource program.
Tips and tricks about this program and GPS how does it work.
What do you need to do to make a route for hiking in the field.
About Garmin maps, what is the structure of these maps and much more.