They used to do an update, but you might call to see if they still do. The frame needs to have a bit of material removed to accommodate the current trigger bar.
As an alternative, you can improve the trigger by replacing the old trigger spacer and trigger return spring with the same current parts. It's been awhile since I did it, so I'm not positive about the spacer, but I seem to remember it needed to be changed to make room for the current trigger return spring.
Regards,
Greg
I emailed Kahr a few weeks ago and they stated they would put the Elite trigger into an early version K9. Not sure if I want to do that right now though, living through the next few months may take precedence.