I've unpacked the official CM13 snapshot flashable zip, replaced the files with COS13 system files and updated the boot.img So finally, I got a full COS13 ZIP, including system, boot and firmware. Untouched. If you want to root, I recommend using Boeffla + Boeffla's su script As it is COS, it includes GAPPS and CAPPS It can be flashed coming from any ROM, since it will wipe and reflash system and firmware, BUT YOU SHOULD WIPE DATA, CACHE AND DALVIK.