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This has been covered a number of times.
Here is the deal. Mazda went to Racing Beat and said, "Make the Protege handle better."
Racing Beat did that with Tockico shocks and using their own springs. They also tried to make a little more power but had to scrap those ideas because of lack of time.
Mazda took the Prototype MP3 and scrapped most of the stuff for more power. They then took the specs of the Racing Beat springs and had their OEM supplier make springs that are proportionally the same (as far as spring rates are concerned) as the Racing Beat springs with a slightly higher but still less than stock ride height. This also probably saved MAzda a bunch of cash.
For all tense and purposes the springs in the MP3 are Racing Beat springs, complete with the red powder coating and the same spring rates (proportionately) that Racing Beat gave them.
The springs that Racing Beat sells on their web-site are basically the same, they just lower the Protege a little more.
That is why there is a difference in ride height between the MP3 and the Racing Beat springs and the percentage of stiffness between the two springs.