The LG Optimus G and the Google Galaxy Nexus have already gotten to taste Android 4.4 KitKat. Now the Sony Xperia Z gets its chance to savor the latest version of Android in the form of an unofficial Android 4.4 KitKat ROM.Aside from the Google Nexus 5, the Xperia Z is the first 2013 flagship to receive a KitKat ROM.
The ROM happens to be stable and most everything seems to be working, but since the mod is based on AOSP, there's no root or recovery here yet. Keep in mind that you have to reboot twice for the Calendar to start syncing, and hit the home button when choosing a mobile network manually.
If you are interested in trying the ROM on your Xperia Z you can download it by following the source link below.
source - XDA Developers