Panhead.....I ran a 1200 Sportster ignition module for many years.....most are obsolete now. There were a few that had a 8000 rpm limit, 2000 rpm higher than what your Evo can handle. The performance modules have a faster, more aggresive ignition curve, and work fairly well with a tweaked Evo in a light bike. The stock modules have a rev limiter at 5200 rpm.
The Sportster module was replaced last year with a Screamin' Eagle unit #32596-96, 6000 rpm limit. Am quite happy with this particular module, as it is similar to the Sportster module, which just quit. SE #32596-96 is also not produced anymore.
If you are running a mild performance cam, pipes and a well tuned carb in a smaller bike, you will probably like addition of a performance module.