Just wondering what all of the engine management people have been reading to figure out all the helmholtz stuff.

One decent source is Winterbone and Pearson's book called something like Design Techniques for Engine Manifolds. It covers the equations necessary for the Helmholtz theorem. Some of the actual theory is in the book as well. You may do some searches on google because i'm sure someone has written a paper, maybe even a thesis over this same topic.