OK re-stating what I thought I already stated
The reason DDM was able to sell them at this price was because of the closeout.
Yes, everyone who was selling them was able to discount this amount if they wanted to.
No Offense to Antonio, but Antonio hasn't driven his car in almost 2 years. I would use someone else for Spring/Shock consulting.
Removing my Opinion
DDM has confirmed that in order for their AutoX car to perform better, they had to install stiffer rear springs on their KW Variant 3s
Multiple Mini Cooper friends of mine ditched the KW springs in favor or the Swift Springs [But still have the rest of the KW setup]
The Solstice Race Team shocked a lot of big players 3 years in a row in the SCCA T2 class with a car that Stiffer rear springs.
SOB, Shabby and other AutoX experienced drivers can also chime in on what works best for them.
But as you say they will probably be fine and if you have good level roads, don't autoX or track the kappa, you might never test out the spring rates in a way that it could matter.
Conversely, In Kelu's case, I think they are a good Drag Racing setup,
but
if you see the "What did you do to your Kappa Part 2 thread" Kelu just suffered damage to Norm's rear diffuser due to bottoming out and hitting the exhaust.
Would that have happened if the Spring rates were reversed as GM intended

In regards to your question
If you change the height of a car it is highly recommend that you get it realigned because the camber of the tires will be off [Angle of the tire in relationship to the road] and thus the part of the tread that is making contact