H&R does make coilovers that work with the xi's. I would not advise purchasing them, though.
Factory ride quality is possible without having to settle with low/poor spring rates. The key to "feel" is in the damping. Cheap coilovers use heavy springs and don't do their homework developing proper damping curves. That is why if you read what people with AST's say, they can double their spring rates, but still maintain a relatively comfortable ride.
I may have a line on some potential other options that are much better than what is available now. I'm not going to discuss them right now since the details aren't finalized. If they can produce, I'll see if I can get a quick white paper and I'll throw it on the forum.