Originally Posted by Bimmer-Bob
BTW, the OP lists the spring rates as backwards. This kit is 60 N/mm (~343#) in the front and 70 N/mm (~400#) in the rear, not the other way around.
Also, I spent about 15 or 20 minutes on the phone with Jeff from Íhlins USA, and he really cautioned against a knee-jerk upgrade of spring rates. He insisted that the kit had been thoroughly R&D'ed and the chosen spring rates had everything to do with the valving of the dampers as well as their unique DFV technology. He also suggested not to increase spring rates by >30% over stock without revalving. YMMV, just putting out what I heard.
Personally, I'm going to try the stock springs first, play with settings a bit, and see how it feels in daily driving as well as on the track.
Thanks for the info/feedback.