To make the 707-320C even better, suggest a few sound adjustments;
- SCREAMING AIRCART: for over 40 years these aircraft used a very loud air cart to create pneumatic engine start pressure:
See this excellent video. I could hear these things in the middle of the night in my bed 4 km away…
There is also a more modern aircraft that produced much less noise, which could be a slider option in the settings menu. Like in this video.
To achieve this see my other post about the APU being optional.
- Higher volume on the N1 fan scream near full power on the external view:
See this excellent video recorded on an old VHS camera, but the sound is excellent.
- More deep bass when viewed from the rear of the aircraft outside, but not overwhelming.