Were you guys running h pipes and x pipes back then?
Most dual exhausts back in the dark ages were independent of each other side to side. The H pipe idea got popular because people got tired of mufflers rusting out on the heat riser valve side. An H pipe kept the off-side muffler hot enough to evaporate the condensation. X pipes- - - -just a gimmick pioneered by custom muffler shops to increase the profit margin!
The only trick exhaust worth fabricating is equal-length header pipes going into a big collector, with each header pipe displacing about the volume of one cylinder. Let the pipes extend back into the collector as they move back from the front of the engine. Each cylinder gets the same scavenging effect that way. Thermistors plumbed into individual exhaust ports on the dyno proved that type of system got the most consistent exhaust port temperatures.
Unequal-length tubes on headers are just eye candy. A good set of ram's horn manifolds are just as effective and they don't get leaky and burn up spark plug wires.
Jerry
