I was looking at the new HS on the Lexus Japan website, and one interesting features they mention is the performance damper. Is this a feature that was included on the American HS? And if not would is be possible to install this component on an older HS?

I know the ct200h uses similar hardware, and apparently when the engineers at Lexus tested the vehicle with and without the dampers, they were surprised at the effect it had on the cars handling. If it is in fact possible to retrofit these dampers on a US spec HS it might make for a fun potential modification.

 

Not that I am aware of. There was a touring or so Hs with a different suspension but its super rare

 

In Canada the Touring Package was called the Premium Sport Package. It includes (to quote from the brochure) a "sport suspension." I assume that the sport suspension has different shocks than other models, but don't know if they are the "performance dampers" you mention.