Special thank to cougar11
update. Also, cougar11 has made sure to include the DualRecovery in the
ROM itself so you don’t have to install it separately after installing
the 5.1.1 ROM.
Grab the pre-rooted Xperia Z Ultra 14.6.A.0.368 ROM from the download
link below and simply flash it via TWRP recovery or any other custom
recovery of your choice, make sure you do a factory reset / wipe data
from recovery before flashing the ROM to avoid bootloop.
÷ How To Install Rooted Xperia Z Ultra
1- Download and transfer the custom ROM you wish to flash to your device’s storage.
2- Boot your device into TWRP recovery.
3- Select “Wipe” from TWRP main menu and do a “Swipe to Factory Reset” on the bottom of screen.
? Note: This will factory reset your device. If your custom ROM doesn’t require a factory reset, then simply skip this step.
4- Go back to TWRP main menu, tap on “Install” and select the custom
ROMs .zip file that you transferred to your device in Step 1.
5- After selecting the .zip file, do “Swipe to Confirm Flash” on the
bottom of screen to begin the custom ROM installation process.This may
take some time.
6- Once your ROM is successfully flashed, you’ll see “Wipe cache/dalvik”
option, select it and then do “Swipe to wipe” on bottom of screen.
7- Once cache & dalvik wipe completes, hit the “Back” button on-screen and then select “Reboot System” button.
That’s all. Your device will now reboot with the custom Rooted ROM you just flashed.