I looked hard for the answer, but my situation may be unique. I've a 2005 Garmin Zmuo 550 and have signed up for the lifetime city navigator. Last time I updated maps the site indicated my 2GB card notwithstanding the unit could not take the full map so I took the option to download to my computer (iMac). Basecamp uses the maps just fine. But a group of us is planning to go the the BMWRA rally at the Biltmore and have been planning routes. I would like to shift the maps to my MacBook, but I'm clueless what files to transfer, or even if the idea would work at all. We are doing backroad routes so the global map included with BaseCamp lacks the detail needed. Garmin's response was "sorry you have to have your device plugged in to do any map downloads, TS". My Zumo is back for exchange as it went tits up due to the contact screen breakdown (sent it before I read the thread about DIY repair). So, can I shift maps, and what files should I be transfering? Thanks for the help!!