According to Koni, the FSDs listed for the 6 are not for the MS6. I asked them myself.
There's other threads on here about the FSD's. Mostly just speculation about how well they would work. I'm sure somebody has installed them by now.
Yep, I've had them installed for almost 2 years now. They are absolutely amazing and worth every penny. I first ran them with RPM sport springs and switched to RPM K spec springs about a year ago. Ride is great even with K spec springs, and I live in downtown DC where our roads are rough. I also track the car at HPDEs, they do quite well in that environment as well. They are as advertised, the best of both worlds.
Let me know if you have any other questions. I can even put you in touch with other members who have ridden in my car for their thoughts.
Looking at potentially going with Koni KDS and springs versus a full HR Coilover setup. Was any customization needed to get them to fit properly in the MS6 or does the standard 6 have an indentical suspsension setup?
Sorry for the delayed response, I haven't checked in on this section in sometime.
Nope no modification needed. Like the Koni yellows these are inserts so you will have to cut the front shock bodies and insert these. That really wasn't that bad and you can search and find more info on that.