HalfLife Gunship Sound replaces the Gyrocopter and Mimiron's Head's sounds with something a bit more clean and robust. You can hear the main sound as the first sample on https://www.youtube.com/watch?v=Oae9btXTXm4
This is NOT a normal lua addon. Do NOT use the Curse client! Manually download and and extract these folders and files into your World of Warcraft folder.
The final folder structure should look like this, with the files in the corresponding folders:
C:\Program Files (x86)\World of Warcraft\Sound\Creature\MimironHeadMount
C:\Program Files (x86)\World of Warcraft\Sound\Creature\Gyrocopter
Restart WOW, and you're good to go!
Issue: For some reason you get silence when banking right. Gone through each sound file - haven't been able to isolate the cause.