This is a nice thread... as it shows, how snowboarding comes down to preferences.
I did not change the springs of my Nortwaves. Yes, they are quite stiff, at the upper limit of stiffness for my some 68 Kgs. But I feel, as they are the same on all sizes, they should be ridiculously soft for a guy in the upper 80s, 90s, ... I like them as they are, because I feel I need a lot of support of my ancles. I feel insecure, when they can be bent too much.
On very could days like at the ECS I feel, that my boots are too stiff, because the shell / tongue becomes stiffer. They still work, when I'm on 100%, but I'm not as smooth as I should be in the flats. So I started thinking about softer Springs. Not for EC, but for very could days and maybe some kind of recreational mode

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At this time I'm looking for a second pair of NWs, mainly as a spare parts reservoir. As soon, as I find them, I will try to cut the tongue of my .900s. Maybe this, combined with a slightly softer Spring will lead to a perfect setup in every condition...