Sony Xperia Z gets unofficial Android 4.4 KitKat treatment in a stable ROM release. So if you own a Sony Xperia Z then you can download and install KitKat right now on your mobile. Remember this update is unofficial and official update is yet to come.
How To Download KitKat In Sony Xperia Z:
If you are interested in using KitKat then follow below steps:
1. Visit XDA developer
2. Download the latest version of Android 4.4
3. Follow the installation and upgrade steps mentioned there
You can check out the 9 minute video below to get a quick overview of KitKat in Sony Xperia Z.