A little fresh air(shocks) never hurt anybody

I’m in communication with a company that seems very responsive.
They tell me the capacity of shocks by wire diameter.
I’m asking if springs can be changed in the field and if 9mm or 10mm springs are available.
About $150/pair
320mm to 360mm eye to eye.

A pair of 360MM shock absorbers of spring 8MM can achieve the load capacity of 360KG. The load capacity of a pair of 360MM shock absorbers of spring 7MM is 245KG.