The info I have on them is (keep in mind progressive):
Front - 457-628, Rear - 177-257
For comprassion sake, heres a few others to compare too.
FRPP B Springs:
Front - 425-530, Rear - 200-300
Eibach Sportline:
Front - 425-630, Rear - 140-295
Last but not least, for comprassion sake the stockers rates (remember these are Linear).
Front - 450, Rear - 210
I used them on the track with Konis and liked them. I just wished they didnt drop the car so much, was always worried about bottoming out. If it helps, Steeda gets some of their springs made by Vogtland.