It's basically a replacement for the stock ignitor which seems to have a tendency to fail based on all of the posts here from people with failed ignitors.
But because its programable, you can also change the timing of the ignition. I'm not really an expert on these things, but basically the spark plug is set to fire right before the piston reaches the top of its stroke. However, sometimes the stock setting is designed more for emissions purposes than the setting that gives the best power, so if you change the ignition timing slightly (usually measured in degrees of crank rotation) it may give a small performance boost. Also, if you change the cams to the older (and better) spec cams, the ignition timing on the new bikes won't be optimal, so you might want to change it to better match the cams. Real engine gurus could expain all of the above in great detail, but that's the simple explanation. Since the Procomm unit seems to have a few different standard maps you could buy one with a 790 map to match the 790 cam. Real experts will probabably want to make their own customized ignition timing map with one of these, but that's beyond my skill level.
