Unlike MS FSX, AH only uses mono sounds for all sounds. FSX uses stereo sounds for your plane and all other sounds are mono. Engine sounds in FSX also uses 4 files to generate the engine sound. Each file is for different RPM, 1 at idle, 1 at about 33% throttle, 1 at about 66% and last one at 100% throttle. This configuration gives FSX the real life engine sound from the backfiring at idle to the supercharger whines at higher throttles. Acutally FSX uses other files with the engine files like prop wash, engine damage, super and turbo charger whines, etc.. Been wishing it for AH. Talking to Pyro about a yr ago, they said they are looking into revamping or changing the sound system engine in AH. I hope they found one and will implement it soon.