Quick guide to flashing Radio and Bootloader;
First of all, I use Wugfresh's Nexus Root Toolkit (NRT). http://www.wugfresh.com/nrt/
It's useful for anyting that might have to do with flashing etc.
Secondy I use 7zip to extract all the files needed.http://www.7-zip.org/download.html
Head over to the Nexus Factory image pagehttps://developers.google.com/android/nexus/images#instructions
1. Download the correct file (version 4.4.3 in this case) for your device
2. Open the file using 7zip
3. Click your way through the archive to you reach the point where you see the two files "bootloader*" and "radio*"
4. Extract these two files somewhere
5. In NRT, select Launch Advance Utilities
6. Flash (permanent) using the Bootloader and Radio/Baseband options
7. Flash the PA 4.4 RC1 and GApps using the Paranoid OTA application
8. Enjoy your PA4.4 running Android 4.4.3!
(if any errors in this procedure, please let me know so I can update the post)
Note1; on Mako/N4, I didn't see GApps for 4.4.3, just 4.4.2, so make sure you get the correct version. If it's not working, just download it fromhttp://forum.xda-developers.com/showthread.php?t=2397942