Bootlogo is centered as the bootanimation logo is.
There are two version of the bootlogo, the first is with the lockpad visible, the second is with the lockpad not visible.
Google logo at boot with lockpad preview
Google logo at boot without lockpad preview
Bootanimation preview (it will be faster on your phone, this is only a gif)
How to install:
1a. Download the bootlogo
1b. Download the bootanimation
2. Copy them to your SD card
3. Flash via recovery
4. Reboot and enjoy!
Special thanks to bitdomo for his imgdata tool.