This link describes how to measure springs, also provides somewhat reliable information effects of cutting springs.

http://www.off-road.com/dirtbike/tech/2002spring/

I did measure and calculate pring rate of valve spring and it is stiffer than suspension spring, tough little springs

Very interesting article - cheers for that!

It's interesting that slamming your car will also stiffen the suspension. I guess the worry is that the shocks are going to accept the adjustment without complaint. Will the shock run happily with higher average compression?

I've just thought of another spring analogy! Instead of describing a coil spring as a torsion bar, it could be described as a wound up leaf spring. It feels much more common sensical that a long leaf spring will be less stiff than a short one. It's all about leverage I guess

Some shocks are able to work in new area, some don't. One big problem will be that shocks are too long, so that causes springs not to stay on place when car goes up, but of course then we can shorten shocks a bit too.

Coil spring is funny in one other aspect, length of spring does not make it to change stiffness, number of coils is what matters, so it is length of spring wire actually. Those round things are anyway real pain to understand

Well i spoke with my tutor today and indead Cutting a coil from a spring does make the spring stiffer.
He said think of it this way. If you have 2 coils and you cut one off, you have a washer!! Can a washer be compressed???
Cheers Adam