Why does ios update 6.1.3 – a 17 odd mb download yet requires 662Mb to install ? Is there patching done on a separate copy of all maps data ? Then it should say temporarily requires 662mb as there description does not make clear whether the 662mb is additional Permanently and all this for better maps in Japan ? Do I have choice in storing maps of Japan on my phone taking up space permanently ? Perhaps it should also state final installed size ?