I'm thinking changing (smoothing) the desired cam angles made the biggest improvement in getting rid of the surging. I would watch the boost drop off and the exh angle went from 122-124 to 114 as the rpm kept rising, repeat and rinse. Just a guess though, I was all over the map changing things and this seemed to work.
A link I found before: https://www.challengertalk.com/forum...93/index4.html pg four. Pector55 coined it