At least Lexus gives you the ability to adjust the volume or turn off the ASC. BMW forces their owners to listen to the synthesized engine noises through the speakers without the ability to turn it off.

 

Getting back to the original question, there is no difference in the engine sound between the standard NX and the FSport. They have the same intake, turbo, and exhaust. Personally, I have never heard any noise from the turbo at all. I have read on this forum that a new intake (AEM) allows more turbo noise into the cabin. I think it's mostly the Bypass Valve, but you might also be able to hear the turbo spool. It's an expensive way to make more noise inside the car,and I would question any power increase claims. It might help with throttle response and turbo lag, though