Spring rates? So do bigger spring rates mean a more badazz slammed look? Awesome.
My point is that :
when the average guy buys adjustable coilovers and lowers his car, he does not contemplate the increase in spring rate required to compensate for 1) the lack of preload and 2) the reduced travel he now has
When a shop that installs a $6K set of Motons or Penskes gets involved they usually set teh lowered ride height car up with higher than stock spring rates, i.e. fronts go from 225's to 500 or more, rears go from 420 to 800 or more.
So in effect the properly lowered car will have higher rates than an improperly lowered car as with linear springs you are dealing with a simple calculation of each inch of travel needed X number of pounds to compress each inch, so a 420 lb spring only needs 420 lbs of force for each inch travelled, and an 800 pound requires 800 lbs to travel that same inch, but if you have lowered your car and now only have 2 inches of travel left instead of 4 you may want to increase your spring rate so you do not bash the suspension into the frame, with 800 lb springs in teh rear it would take 3200 lbs of force to compress the suspension the remaining 2 inches, if a person bought "off the shelf" lowering coilovers they may have 450 lb springs and therefore only need 1800 lbs of force applied to compress the suspension.
This is why everyone that orders coilovers from me has a discussion with me about driving needs and wants and if they intend to ,lower the car and by how much.