Lighter springs for Z axis

[David B.]

So far, I'm very happy with my new NXT EVO setup. The only Thing I wish, is that there were a few different strength springs for the z axis, as there are for the x and y axis.
Any idea where I could get a softer spring (I need 2 for a HOSAS setup).

https://home.mycloud.com/action/share/eff9a8d3-da4f-4255-b9a1-3c128ccbbbde