I just finished installing the Apex J-Frame spring kit in the 442, and for now let's just say, it's pretty sweet. Where there once was stacking and a pretty heavy trigger, there's now a somewhat lighter one, that's smooth and consistent throughout. (Need to find my trigger gauge to see how much lighter it is now though.)
I followed the two videos Apex has on YouTube, and they're pretty good for walking you through the install. I will also second the advice that you invest in this tool if you plan on doing the install. My thumb would have thanked me, rather than had a screwdriver blade jammed under the nail. First time in a while I wanted to pass out while doing some gunsmithing.