Each engine combo is going to work best with a particular timing curve. With the wide production variation in timing, the majority of boxes are a crap shoot. Without a dyno and timing light, you'll likely never know the difference.
I looking for a performance upgrade you money will be better spent on Cams , Higher compression pistons ect as most rev boxes effect will be hard to notice.
But for the price and ease of installation they are not a BAD idea, and the stock black boxes do seem to wear out at times.
Personally I like the smaller outer rotor ignitions, lighter than full size flywheel but not as light as the IRK unts.I know this was not the original question but since were on the subject of electrical systems I added the info.