This is my home-build throttle quadrant. Two Power Levers and two Condition Levers (note the reverse locks) Has an Elevator Trim switch in Power Lever #1 and Autopilot & Autotrhottle Disengage buttons in Power Lever #2.
One of the most audible difference is when engines idles (Garrett idle speed is at 70% RMP) is a very noisy engine in ground operation.
The challenge was hard because I must deal with the non open part of FS9 architecture, the non conventional area for tweak.
I did a great search for see if there was a way to interact with the internal FS9 sound engine with no success. This was my first strategy approach; intercept the main FS sound system and try making it operate in a Garrett way. This was not possible.
The final approach was done by working over what the pilot sees and hears; in other words, let the pilot see the gauges with the Garrett engine behavior and accompany this with a believable and accordingly engine sound.