[MrMigs]

ehh for a spring, the things to look at are mainly consistency in production, so when you have an 8k spring, it really is 8k and not 7.5k for example. And then, you want to make sure that the spring rate is tested in it's full range from standing height all the way to maximum compression. And you want to make sure (assuming you want linear springs) that the spring rate stays at 8kg/mm through its full compression range.

I know Tanabe springs were made/tested in that sort of way bc I used to work there. Swift, I believe is produced in the same standard, or maybe better. Also, the type of metal that's used is something to consider... I don't feel like doing the actual research, but I recall Swift being made by some sort of composite with great properties. Meh...