I am skeptical about this whole thing. There could simply be a poor connection at the battery/starter which is the case 99% of the time - because these connections experience heat/cold/humidity cycles for years, while at the same time being the most sensitive connectors on the bike when it comes to degradation because they have to conduct the most current among all circuits on the bike. Just cleaning connectors with 100-200 grit sandpaper (and stuffing with dialectric grease for future protection against elements) would noticeably reduce the extra resistance a poor connection introduced, thus allowing for more current to flow during cranking. Putting a new wiring indirectly forces a better connection at the battery/starter terminals because the connectors are clean. So, what is observed is the combined effect of clean connectors and thicker wiring. My educated guess would be that 95% of improvement is due to clean connections, and only 5% due to thicker wiring.
The real test would be to take a bike which seemingly suffers from poor cranking. First, clean battery/starter connectors, re-tighten, and measure what current goes through the circuit whena cranking. Then, install a new wiring, and measure again, and compare both.
An example: my friend had trouble starting the bike. It would barely turn. He replaced two or three batteries, was fully charging them, etc. And was scratching his head at this problem. The bike would start with a jump starter with no issues. What turned out to be the problem was poor connection at the battery. All it took was to have a dirty and oxidized terminals coupled with the fact that the screw at the positive terminal was not tight. When he tried cranking for a couple of seconds, his positive terminal was getting so hot, you couldn't hold the finger on it. All it took was a piece of sandpaper to clean it all up, and a quality screwdriver to tighten the terminal.
BTW, in any high current application, follow the heat to figure out where the connection is poor. If the cable is not even warm when you crank the bike for a few seconds, then it's not the problem. A warm connector points to a problem.