I put KYBs on both of my roadsters and thought at the time they were kind of harsh. They have some miles on them now, probably 5k+ and I thought about them while driving a few days ago and I am now quite satisfied with them.
Thanks.
Did you put on the KYB's with the separate XF part number, and not the SLK part number? They are both supposed to fit. There was speculation in an old thread that maybe they valved them differently for different car weights, but the SLK and the XF are actually pretty close in weight. My understanding is that they did have different stock wheel sizes. Never heard exactly what was supposed to be different between the SLK and XF KYB's.
The Bilstein B6's also have separate numbers for parts that will fit both. I'm trying to figure out if they are really different, and if so, how.