I'll probably just end up doing 10k in the front. Don't want to deviate too far away from the original spring rate otherwise I'm going to have to revalve the dampers.

 

I'd recommend a 12-13 kg/mm 8" spring in the front and 9 kg/mm 7" spring in the rear. This seems to be the best combo of firmness and performance.

 

Too late, I bought the 10k springs The fronts were 9k originally so 12-13 is too much for a daily driver. Plus I rather not spend the money to valve the shocks since I have other projects going on.

 

What brand of springs did you end up going with? I'd like to see if say a hyperco or eibach 10kg springs mated with a helper springs will give you the ultimate track/street setup. And did you go with 7 or 8" springs?

 

I ended up going with 8" Swift springs in the front because I got a pretty good deal on them. Was going to end up with Hyperco since I was happy with them in the past, but quite a few of my friends who tracked their cars switched to Swift and liked them better due to less mechanical lag and unsprung weight. We did a spring dyno and the Swift had slightly better tolerance than the Hyperco. We're talking only 5lb difference so I'm just nitpicking

Haven't installed the springs yet. Still waiting for my thrust bearings to come in.

 

The higher-pitched springs like Swift makes work very well for anyone that likes to drive; the road feedback is enhanced through a firm initial rate, yet will yield to larger undulations.
I figured this out some 16 years ago, using springs sourced from Mazdas, and a few Japanese lowering kits for a project, but until just recently, did not know of a source for replacement, or coilover springs.
I had a car that would drift at 100, very controlled, easy to drive, yet would take bumps better than my then stock SC400.
I'm helping my Dad put together his IS300 Sportcross for rewarding, yet comfortable transpo using Bilsteins, and hope he also winds up with some Swift springs(7K,5K) when it's all done.

 

My thrust bearings came in yesterday and I finally got around to install them in addition to my front Swift springs. As expected, the Swift 10k springs were more compliant than my older 9kg/mm springs. No more coil binding and less body roll. Now I'm going to have to get a new set of Swift 8k for the rears to complete the set. You can tell while driving that the rear likes to dance around, unlike the front.

 

How much are the swift springs?

 

http://www.hypercoils.com/DOC/spring...or-hyperco.xls

In the quest to ride lower with flushed wheels, I'm thinking about going 14/12 with swift and cup kit... at (12/10) ride is comfortable, maybe I'm just used to it.

http://www.swiftsprings.com/products-sport_springs.html

The price is about 100 bux a piece.