The difference is most likely in what you can't see . Quality in the components and manufacture.
BINGO!
Just because you cant "feel" the difference does not mean they are not better.
Wires are a consumable like a spark plug.
The better the set at the beginning the longer and more reliable they will last.
With wires you want the lowest resistance in ohms.
You can measure that with a multi meter.
ford racing wires have a much higher resistance than the more expensive ones.
I bought some taylor thundervolts.
i think i paid like 60 bucks a set and they are far superior to ford racing in the resistance and the quality.
(I got 10,000 ohm resistance from my old ford wires, and the new taylors where 50 ohm)
Should perform better and longer.
Well worth the 20 extra bucks over 39.99 ford wires.
Here...
http://www.summitracing.com/parts/tay-84692/overview/make/ford/model/mustang
Also, I love LMR, but occasionally you can find the same or better options from a local parts store or
online from the manufacturer or another middle man.
As always, Just my 2 cents worth.
Do as you see fit.
Doug