I can tell you that I have not seen anything on Mytsn at all or in any manual that tells me spring rates, however, the ranking of course from softest to hardest is Orange,White,Yellow, Red, and Blue being the hardest.
I posted an article in the Serpent 705 forum a few weeks ago in which I used the Integy (Xipp) spring scale and came up with some very interesting results.
Go to the Serpent 705 forum and look for page 53. You will see the setup I used to determine which pairs were closest to each other to be used as sets.
I will have to re-do some of the springs to give you the range.
Once I was finished matching pairs I wasnt concerned with the end results.
I do know that on average they were 3-5 l"bs between each color .
Send a Private mail and I will get it done tommorow night and let you know approx the avg spring rate in "lbs.