The first upgrade should be a better transmitter either a 7C or a 9C.
Next Direct Heli's blue gear with hardened shaft
Next Aluminum swach plate
Next Brushless
Next G-90
Next Dual tail motor or DD
On the way, try every blade made.

I didn't quite do it in that order, but I wish I had. I haven't seen any good reviews on the CNC head, so skip that one.

Only upgrade when you are ready for the next step, because at any point you may decide to just move to a T-rex and skip some of this.