This is easily one of the best tuning links I've ever used.
I had a problem with my SP101 when it came home, in that the trigger assembly would not re-seat due to burrs in the latch channel of the grip frame. The picture in the link showed the problem clearly. I used a 1/4" dowel with 1000grit to polish the burrs in the frame off. Worked perfectly.
I used a 1/4" dowel and a patch with JB polish to clean up the latch hole, as I didn't like the drill bit idea, and I polished latch and plunger by placing the dowel in the parts, and turning them in the patch and polish for a nearly mirror finish. This really minimizes drag without dimensional changes on any parts.
I used a Dremel for polishing the other parts with buffing rouge, slower than emory, but the finish might be better. I replaced the trigger return spring with the 8lb Wolf, and haven't had problems.
I haven't touched the trigger/sear yet, as I want to shoot it enough to see if wear patterns tell me where trouble spots are hiding.