I think it is the same like with carindb file - to reduce the image it is necessary to now how files (i think KN074EU16X11T01.DB2_XAC, KN074EU16X11T01F.DB2_GDB or/and KNT074EU16X09T01) are compiled! I do not think that another possibility is exists.....

Try to burn to a DL disk....... If your navi could not read DL disks try to update SW (dealer will help you to do that)