I have read and followed previous instructions on how to load OSM maps onto my new 830. To display the new OSM map the original maps should be disabled. My concern is storage as I want to load several countries using OSM for touring and with up 30 or 40 days of routes saved will the 830 get overloaded? And should I remove the base maps rather than disable them? Previously my 810 allowed me to use a memory card and storage was not an issue. A guide on storage will be helpful please.