I installed KYB's on my 88 GT last month. There were a few issues that I had with them.
I had read somewhere about a clearance issue with the knuckle. There is a small "ridge" or "bump" on the back side of the casting where the knuckle fits into the strut- clevis. This "ridge" needs to be ground down a bit (few millimeters)according to what I read. I believe there is a problem getting the proper camber settings without removing some of the material. However, I can't say if this is actually a problem because I ground mine down just to be sure and the issue appears to be hit and miss. Some cars have a problem while other don't. It's probably a casting tollerance issue with the knuckles.
Another issue/problem that I had was that I did not pay close enough attention to the alignment of the top-mount relative to the strut-clevis before dis-assembling the original struts. Therefore when I assembled the KYB's I did not get the alignment exactly where it used to be. This caused the strut-clevis to not line up perfectly with the knuckle when I went to connect the two. I had to wrestle and force the joint together and then had a hell of a time getting the strut bolts to go through the two attachment holes. This is not a problem with the struts, but a mistake on my behalf.
The last issue I found was that similar to the front KYB shocks, the struts were just a bit longer (about 10mm)than the stock units at full extention. This means that the suspension will have an extra 10mm of rebound. This is probably not enough to cause any handling/performance problems. But I had purchased a $50.00 strut alignment tool (J.C. Whitney) to insure that the camber setting was maintained after removing and then attaching the strut. This extra 10mm threw off the tool enough that it was rendered usless and I had no idea where the camber setting would end up after re-assembling the strut/knuckle joint.
The KYB's in my opinion are a decent buy. The perfomance increase that I experienced was only noticed on large and sharp/quick bumps. In most normal driving conditions the KYB's performed pretty much like the stock units with just the slightest increase in damping stiffness. This means that they have a nice smooth ride for most driving situations and become a little stiffer as the driving becomes more intense.
[This message has been edited by turbotoad (edited 05-19-2003).]