Root required!It is recommended to make an nandroid backup before changing system partition files.Updating a system app decreases phone internal storage, because the update is stored in /data/app and the original apk is still in /system/app.System app cleaner will automatically:- backup the original apk in /sdcard/system cleaner/ (in case you want to restore the original apk)- delete the apk in /system/app- move the updated apk to /system/apk- delete dalvik-cache(optional but recommended)- reboot device (optional but recommended)By doing this, a considerable amount of internal storage will be freed.