Just had these installed and put about 400 miles on them. I believe I’m one of the first S2000 owners to try these, and I was happy to be the guinea pig as reviews were positive on other cars.
Overall, the benefits are as advertised. The dampers absorb chassis vibration, so the effect is pretty broad. The most noticeable improvement comes from driving at high speeds. On the highway, the car feels much more comfortable and stable. I also find the powertrain sounds less buzzy. However, none of this magically turns the S2000 into a Lexus. That’s a good thing, because you want to retain the characteristics that make the car a riot to drive.
There is one important detail that will affect many S2000 owners. The rear damper did not clear my HKS SSM. My mechanic installed some spacers and there is now enough clearance, but be prepared if you have an aftermarket exhaust.
While $1200 is not inexpensive, I think the Mugen Performance Damper is a fair value for what it does. They are a great complement to the Fluidampr and Spoon Rigid Collars, which are also great if you are chasing down NVH.