Is there a way to swap these effects? Basically I have two versions of the same helo and the one with the most realistic VC has a not so good rotor effect, whereas the other is perfect. Is it possible to replace the bad with the good version?

You can swap interior models from the exterior if they are true FSX models, but other than that, if you are referring to the rotor animation, nothing you can do about that without being the developer and having the source files.

Ah. Yes it was the rotor effects. Thanks anyway.