[KDN]

At best there are 4 or 5 changes.

That's because there are only 4 or 5 files governing each engine's sounds, modded or otherwise. If you think there's some kind of magic difference between the way the original engine sounds are set up vs. the modded ones, you're in for a surprise.

So where is the difference between the modded sounds lack of variation and "aliveness" of the original sound attributed to?