One more thing about collector and why they work. As the pulse inters the collector it quickly expands creating a vacuum right behind it. This vacuum then pulls the next pulse out which pulls the next one etc....... The 180 degree headers do this very well since the firing order in each collector is one after another. They crisscross the engine with pipes so each side has one after another firing order.
Using you calculations of 55" x 1 3/8" pipes, the pulses would be really shooting out at a high rate of speed if you could keep the pipes hot for the whole length. Ever put a long straight pipe on a lawn mower? That will create a lot of vacuum in the adjoining pipe.
Joe
