The crossover is to balance backpressure throughout the system. Dyno tests done in the late 70' early 80' proved the value of this arrangement and it has become a standard. Jim's setup sounds great
,especially when winding it out through the mountains while driving enthusiastically through the more twisty sections. The walls of the valleys and trees served as an echo chamber to make the effect even more intense. I hope to follow Jim thru the mountains again sometime.
Dave951M