1. Downgrade to 4.2 Nordic version. Optional if youre 4.3 is already in Nordic.
2. Relock bootloader.
3. Use SUS to download and install the 4.4.2 update.
4. Decrypt and create your own FTF from the files downloaded by SUS.
5. Unlock bootloader.
6. Flash CM11 KK boot.img using fastboot.
7. Boot to CWM, flash supersu update zip to root the phone
8. Relfash STOCK Sony Kernel using the FTF created in step4.
9. Enjoy ROOT access.
10. Optional - relock bootloader.
Disclaimer - by following the steps, your warranty is VOID now. BUT you get to have the latest version of Android, ROOT and customization for your phone. I have made necessary backups to restore everything to STOCK, including DRM keys in case I need to go for warranty.
Edit - i'll update later with download links for flashtool, SUS, CM11 bootimg, chainfire supersu update