I'm curious as to how Joopitar8 or anyone else here might have fared trying the K4/K4r upgrade,if you did go ahead with it. I thought the company was great on customer relations and timeliness; in my particular case, though, I didn't notice a dramatic change in the module's operation...maybe less attack transient on the filters at high level, that's about it. Weigh in with your experiences,please!