[Xperia Z Q&A, Help & Troubleshooting] NoFlat:
Yes,its a 6603, and it show me: unlockable.

Now i been tried to flash in "Bootloader-locked-mode", but after point 7.) Boot into CWM & flash the MIUI 3.9.7 ROM .zip:

it stops at 95% (permissions) and go to bootloop.

I dont wanna unlock my Bootloader at the moment.

Damn

For Locked Bootloaders follow this guide from @kevev

1.) Read through all of these instructions before proceeding!

*****All .FTF files are flashed using Flashtool.*****

*****These .FTF files will NOT flash a baseband because we need to keep the stock radio bands.*****

*****If you flash an incorrect BASEBAND you may loose LTE or all radio functions!****

*****I have included the .166 T-Mobile US C6606 Baseband .FTF in case someone needs it.*****

2.) Place All MIUI ROMs zip files on the external SD card.

(This is important as later on you may have issues placing files here after flashing the first ROM.)

3.) Flash this rom:

C6603_10.3.1.A.2.67_Generic ES_NO_BASEBAND.ftf

4.) Root the device:

Instructions: http://xdaforums.com/showthread.php?t=2386405

Notes:

When you boot after flashing the NL .FTF kernel file go into settings --> About
Tap on "Build number" a bunch of times till you see this on the screen "You are now a developer".
This will allow you to enable "USB Debugging" in the "Developer Options" settings menu.
Also enable "Unknown Sources" in "Security" in settings menu.*****

Ignore the fact that your SD card will not mount. That will be fixed after MIUI is installed.

5.) Install dual recovery:

http://xdaforums.com/showthread.php?t=2261606

Notes:

When running the .bat file enter "1" for SuperSU.

When you see this message "Look at your device and grant supersu access" you may not see
the supersu window on your device if you previously allowed access.

6.) set "vanilla" cwm as default instead of Philz recovery:

Do this by going to sdcard1/XZDualRecovery/XZDR.prop and change the line "dr.vanilla.cwm=false" to true

7.) Boot into CWM & flash the MIUI 3.9.7 ROM .zip:

a.) Shut down the device.

b.) Power on the device.

c.) Press Volume Up when you see the Green LED.

c.) "wipe data/factory reset"

d.) "advanced" --> "wipe dalvik cache"

e.) "install zip" --> "choose zip from /storage/sdcard" --> "miui_l36h_lockbl_3.9.27_498ecdaeac_4.1.zip

f.) Reboot.

g.) Select "Yes" on the "Disable Recovery Flash" screen. The device will reboot.

*****You will have only a blank screen after the black "Sony" screen. This is OK. Continue to next steps.*****

8.) Boot into flash mode and flash .253 kernel:

a.) Keep USB plugged in and open Flash Tool.

b.) Hold Power + Volume Up until the device reboots(Screen goes blank) and release buttons.

c.) Quickly Hold Volume Down until you see "Device connected in flash mode" in the Flash Tool window.

*****If you do not press Volume Down quick enough the device will bootloop again.*****

d.) Flash C6603_10.1.1.A.1.253_Generic DE_KERNEL_ONLY.ftf (Do this quickly as the device may reboot randomly!)

e.) Reboot.

f.) After booting up and moving through the initial MIUI setup menus, wait 5 minutes before proceeding to the next

steps.

9.) Boot into CWM & flash the latest MIUI-Z ROM .zip just like you did the 3.9.27 version:

a.) Flash the .zip

*****Make sure to select "Locked Bootloader" in the Aroma Installer which starts after begining flash!*****

(You can install the "Beats Audio" mod if you wish.)

*****You will have only a blank screen after the black "Sony" screen. This is OK. Continue to next steps.*****

b.) Reboot.

c.) Select "Yes" on the "Disable Recovery Flash" screen. The device will reboot.

10.) Boot into flash mode and flash .67 kernel just like you did the .253 kernel:

a.) After flashing the kernel Reboot.

b.) After booting up and moving through the initial MIUI setup menus, wait 5 minutes before rebooting again.

c.) Enjoy MIUI!

MIUI Update Instructions:

1.) Boot CWM & Flash the latest MIUI-Z ROM .zip:

a.) Wipe Cache & Dalvik Cache.

b.) Flash .zip .

c.) Reboot.

*****No need to flash the .67 kernel*****

Here is all you need thx again @kevev