WOW i could write a book on this subject , And we have it set for a section on our upcoming video sessions.
Any way heres the short version:
Once upon a time (heard that before

) before every household had electronic stuff all over the place , no rockets ships or satelites it didnt really mater if the ignition cable was noisy . I remember our first TV as a kid and every afternoon ( before my dad got home) I watched Mighty Mouse (try to save the day) and a old 56 Ford would drive by our house and mess up out TV , ruining a part of Mighty Mouse. Never knew if it was worn out generator or the plug wires!!!
A solid conductor wire conducts high voltage from end to end with a wide band frequency like a ocean wave. This wide band creates electrical noise that travels thru the air in some cases for a long ways. This creates a problem with any and all electronic products.
The first supression cable was a nylon center impregnated with bits of ground up glass and carbon. The electricity went from carbon ( a conductor) to the glass ( a non conductor) causing a filter effect that did away with the ocean wave of travel and created a smaller much more contained frequency wave form. This filtered out most if not all of the problem radio frequency.
This cable was used on all factory cars from the 70s onward . Consider problematic based on breakage due sometimes to heat and vibration and other time due to a serve tech jerking on it!
Todays supression cable is made in many variations like spiral wound , carbon centered etc. Marketing is big here for sure !!!!!
Suppression cable can be used on a flathead , A solid wire at idle may use 5000 volts based on compression, air fuel mixture. The same vehicle would still use 5000 volts with supression cable !!!!
Electrical fact: Secondary cable resistance doesnt have any effect on firing voltage !! Only open cables , and bad connections cause the cable to increase the voltage . Plug wire resistance of 1000 ohms per inch is the spec on come vehicles.
Resistor cable kills the famous "blue spark" making it appear orange !! Same with resistor spark plugs!
The cable doesnt care if the voltage is six or 12 volts works just the same.. a six volt car needs the same voltage to fire the plugs as a 12 volt car. Its just that the 12 volt car has more reserve voltage available compared to the six volt car..
Bottom line is that if you have a early Ford v8 with no electronics "use the solid wires . Last forever and you dont need to replace them hardly every.
This discussion could go on and on in regards to connectors , wire ends etc....should be enough to start a discussion as is 
