We just installed the Íhlins system on our STi project car last week and the improvement in the suspension is very impressive. The first thing you notice when taking them out of the box is the massive 45mm pistons. They feature an inverted design like the factory STi suspension. You can see them in the photo in the link- www.WorxTuning.com/specials/specials.htm
When installing any coilover in general, you will have some sacrifices in daily drivability, in exchange for increased suspension performance. In nearly 1000 miles since installation, we would have to say the only sacrifice is a slight increase in road noise transmitted into the cabin. Beyond that, the system overall is far superior in every aspect. Keep in mind that our STi is daily driven nearly 100 miles. Gone is the slight harshness of the factory suspension when encountering bumps and slight imperfections in the road. The Íhlins system is much more compliant, but much more capable of keeping the vehicle stable during hard cornering. There are 16 positions of dampening adjustment which allow you to take the vehicle from more road friendly, to more track friendly in a matter of seconds. In testing the settings, we found that we could comfortably take one of our favorite curves (a sharp 90 to the left) considerably faster than we ever would have before with the stock setup. The vehicle stays much flatter and is more controlled and predictable. The rates on the springs are 230 lbs/in front and 171 lbs/in rear. The fronts are stiffer than stock and the rears are a happy medium in the middle of the factory progressive rate.
Íhlins has truly lived up to every one of our expectations. When a company is so deeply rooted in professional racing suspension such as they are, you would not expect any less. We can see why their systems are the choice of so many of the leaders in racing, including numerous competition Subarus. We have yet to see what they will do on the track, but anxiously await the chance (yes, we are drooling at the mere thought