Here are some spring rates from the Spring Rate post.
Neuspeed Race spring:
Rate: Front- 455 Rear-360
Drop: Front- 2" Rear- 1.75
Linear spring
Ground Control coil-overs (sleeves):
Rate: F-380 R-250
Drop: F&R- .75-3.5"
Linear
These can be custom rated in 25lb increments. (Eibach springs)
Quote from member aogawa - "Also, does anybody have specs on Skunk2's coilovers. I've emailed them and they said they had the same spring rates as stock. Then I emailed them again, knowing that was wrong, and then they said 450F/350R. "