Details In Garmin Map

I am able to use Garmin maps sourced from http://shonkylogic.net/shonkymaps/ on Oruxmaps. These Garmin maps can be freely downloaded.
The problem I have is the way Oruxmaps displays different layers or details on this garmin map.
If I view this map on Garmin Mapsource, I can get very good detail when zooming in close. In Oruxmap, it does not increase level of detail when zooming in closer than 50km.
Is there a way of increasing detail for Garmin maps in Oruxmaps?

I have set zoom to be "combined zoom" for all zoom settings
Garmin map settings used:
Use Antaliasing
Show POI
Show Line Labels
Letter size = 7

OK, I have found the solution (thanks to garrick.leonard)..."garrick.leonard" replied to other posts for people having issues with Garmin maps. He suggesting "Joining" the Garmin IMG files using GMapTool. I have tried this solution and found it "unlocked" the details in the Garmin maps. I now have full detail in OruxMaps for the Garmin maps.