It's easy. Spring rate (lb/in) is inversely proportional to the number of active coils. I don't know right off how many coils the stock spring have, or what the rate is, but here's an example.
example spring rate of 250lb/in with 10 coils
cut off one coil, you get a spring rate of 250 x 10 / 9 = 278 lb/in
Somewhere around here is the stock spring rates, and you can easily count the number of coils by climbing under the car with it on the ground.
Of course, the stock shocks are insufficient even for the stock springs, so stiffer springs will make that floating even worse.
Anyway, there is nothing wrong with cutting springs if you do it right. Feel free to play around. You may learn something from it.
Asterix