I owned and built several N54 platforms and this one sounds near nothing like any of them. When built, the N54 sounds much more vicious than what you have in this game. Here’s a few examples of how it should sound.
Interior:
Stock >> https://www.youtube.com/watch?v=FXtOl4pMQBk&t=181s
Built >> https://youtu.be/uATEoswOx3c?t=10
Exterior:
Stock to tuned >> https://www.youtube.com/watch?v=b5U5jhlbrLo
I know the vids show 335i, but it’s the same platform. They sound almost the same.