The Wolff spring kit for J-frames reduces the mainspring from a whopping 8½ pounds to a low, low 8 pounds. In other words, don't change the factory mainspring.

You can reduce the rebound spring from the factory 18 pounds to 15 pounds without compromising reliability. Don't go lower.

The real improvement in J-spring trigger pull is in smoothing the action. While this can be done by an advanced amateur, it can be misdone by some folks who call themselves professionals, so be sure you know who's doing the work. If you can afford it, send it back to S&W for a Master Action Job. I have one gun that had this done, and it makes a 14 pound pull feel like 8 pounds, and it always goes "Bang".

Buck