[Xperia Z3 General] metuskale:
Well, in this guide I will try to concentrate all the process from a Stock Z3 (D6603) to a fully rooted, unlocked bootloader, custom rom and recovery, modded kernel and xposed firmware.

AS ALWAYS I WONT BE RESPONSIBLE FOR ANY DAMAGE, WAR, OR DEAD UNICORNS. PROCEED ON YOUR OWN RESPONSABILITY

Pre-process drivers:

Get fastboot drivers from here: https://mega.co.nz/#!upQkWCpA!BCvvsQR6Ee1gfmzAAGCeIMmFek2AaM0r_9HGWVNw8tM

Get adb+drivers from here: https://mega.co.nz/#!upQkWCpA!BCvvsQR6Ee1gfmzAAGCeIMmFek2AaM0r_9HGWVNw8tM

Z3 Official Drivers from here: https://mega.co.nz/#!v8JkkZAQ!w9ERWMs0L1UmWf_N3oCT4JgFdfU9NUFT7Wjv7D_bBh0

First of all you need to gain root privileges:

Download stock firmware (FTP format) https://mega.co.nz/#!D5ZXmJKZ!XWD6dae-NwKECGctrFsetFlODcf6EQMMYf22fCPHo2g​

Download FlashTool (To flash FTF format) https://mega.co.nz/#!D5ZXmJKZ!XWD6dae-NwKECGctrFsetFlODcf6EQMMYf22fCPHo2g​

Download GiefRoot and unpack it https://mega.co.nz/#!yxQFQbzK!KeA0u1i6KwKetj1aAaSLUZ_qiih1N0uox0GGes700J8​

Flash the stock firmware using flashtool, click on the bolt, select the FTF file downloaded previously and follow instructions​

Note: The screen says press back+plug USB. It is not back button but VOL+ Button​

Now skip configuration process, you will loose it all so it is not necessary but nothing happens if you want to waste your time.​

Once skipped go to Settings > About Phone and tap 7 times on Build number to enable developer options.​

Under developer options enable Usb Debugging and Mock Locations​

Now, in settings enable unknown sources and disable verify apps ​

Put your phone in Airplane Mode​

Connect your phone to the computer and open the install.bat inside the folder of GiefRoot​

Note: Probably a pop-up will show in your phone asking to allow USB debug, check the "Always allow..." and press OK​

Now follow instructions on the CMD screen​

Note: It will probably fail the first time, just start again from install.bat point​

Now let's install a recovery (it wont be the final recovery because this is changed by installing roms, we will stick on FOTA one. A few steps below.

Download ES File Explorer: https://mega.co.nz/#!j0xxESqT!k1VHSKi86lBgdh8NPbxmb3Q9FKFWDup7gAt-_uWkWCU​

Download ZU Recovery: https://mega.co.nz/#!Ll4UVLTS!A8w4NeleaxjXBLQdUbZLtzGZRpPefX71rp27aCNV_mk​

Enable root and mount system r/w.​

Extract the ZU Recovery and open install.bat​

Choose option 1 and follow instructions.​

Note: You will have a new App named NDR Utils, use it to reboot the phone.​

Let's backup DRM keys:

Download TA-Backup: https://mega.co.nz/#!v0wgDCRR!xJBrmo1FfdvQQcFzK6ZO4dEfUi1YLaNGEl8XMaKu18s
​

Extract TA Backup​

Run Backup.bat​

Keep the file generated well saved.
​

Now, we will unlock bootloader:

I won't explain this point, I will recommed you follow this guide from the Official Sony's web: http://developer.sonymobile.com/unlockbootloader/unlock-yourboot-loader/ it is very clear and includes all checks needed.

Now let's install a custom ROM to proceed to FOTA recovery:

Download PacMan custom ROM from here: http://xdaforums.com/z3/development/rom-pac-rom-lp-mr1-beta-1-t3099454​

Flash it as usual​

Let it boot and proceed to next step​

Now let's install the FOTA recovery:

Download FOTA recovery image: https://mega.co.nz/#!38xxBZZJ!2jwbChc-XFlilltodA7R0VQzQTnbf8EPbUokR38C4Yg​

Once the ROM has booted put your phone in fastboot mode:​

adb reboot fastboot

Or turn it down, hold vol+ and plug the USB.​

Then flash the FOTA recovery:​

fastboot flash recovery <downloaded.img>

Then reboot your phone:​

fastboot reboot

Now we can proceed to install PacMan ROM again (in case you lost it while flashing FOTA):

Download PacMan custom ROM from here: http://xdaforums.com/z3/development/rom-pac-rom-lp-mr1-beta-1-t3099454

You can use this kernel along this ROM too:

http://xdaforums.com/z3/orig-development/kernel-m5-kernel-t3045319

Get the permissive version in order to allow xposed to run.

xposed: I am testing it right now, I will explain it as soon as I see it is stable.