Before sending that level of $ perhaps fab up a “proof of concept” with thin wall aluminum electrical conduit you can bend yourself, and try it out for a few thousand miles, not expecting it to last beyond a MPG testing period?
I doubt even having the correct pulse arrive back at the exhaust valve seat at low rpms will improve BSFC more than a few percent.
I would spend the $ on some wind tunnel testing time, or cheap coasting down steady grade hills.
I don't expect it to be a huge thing by it self but combining many tricks the whole thing should be pretty cool. My main thing i if I can improve the low end TQ of the engine it can operate at a lower RPM reducing friction and giving more time for the pressure to work on the crank before being released.
I already have a great hill I do red-neck wind tunnel testing on, I figured out I can block 1/2 the grill and a few other things on the front end and pick up a few MPH at the bottom. I think I may have gotten that idea from you years ago.
HRD I think there may be a simpler path than 8ftlong primary tube headers. An anti reversion chamber in the exhaust near the end of the collector would likely give you some of the increased low end torque you are looking for without the huge expense and pain in the [censored].
Some 4/2/1 headers and longer than normal collectors may also help.
