Yes, I only hear it at low speeds with my windows down. If you still have the original dampers sitting around, compress them by hand and let it extend again on its own and you will hear the noise I am referring to. It is more of a fluid hissing sound. We might not be talking about the same thing. If this is what you hear, it is normal and I have heard it on many cars with factory parts still, mostly on cars with relatively high damping rates.
Most entry level dampers, like the Eibachs, are constructed in the same fashion as OE parts. They get their higher damping rates by using smaller orifices in the valves. This means the fluid is flowing through the valves at higher flow velocities (yet lower mass flow rates) which is probably why you notice it more.