Do you overclock your CPU and how much? You should if not
But you won't get much faster than 2600K @ 5.0Ghz. You can go 3770K @ 5.0, but you have to delid it for that.
Furthermore your GTX570 is also a quite good card for FSX. 580 offers and edge, and 680 ain't faster.
So you see, you have a pretty good thing there.
Good luck nevertheless!