They can conduct maximum amount of amperage to the spark plugs due to their internal construction. This is especially beneficial if you're running a hotter coil which is lots of times necessary with addition of a power adder (i.e. turbo, supercharger, nitrous). They're constructed with actual metal wire wrapped at 200 turns per inch around a magnetic core, which eliminates radio frequency interference (RFI). Other aftermarket "performance" wires lots of times just use a silicone or Kevlar core embedded with metal particles which breaks down as voltage passes thru it. This way they can use less metal wire and still be impressive in little bench tests that compare one wire against another in low voltage resistance tests. You'll see them advertised as "ferrite" or "spiro-core" or "superconductor" or a multitude of other catchy meaningless names.
For average daily use, they're probably overkill, but they will probably outlast the vehicle, rather than needing replacement every few years like most other aftermarket plug wires. They're incredibly expensive though...I priced their KV-85 race wire set for my Explorer, and they were around $140! Their Powersports (i.e. stock replacement) series weren't much cheaper...I think they were like $109 or so.
For a decent stock replacement, I like Carquest's premium line which is made by Prestolite, the largest supplier of OEM plug wires. They look, feel, and fit just like original equipment. NAPA's Belden Max line is also very good.
Definitely avoid the better majority of the aftermarket wires though...Especially those found in "discount" auto parts stores like AutoZone, Advance, etc. Most are made very poorly and are designed to fail within a couple years. Advance Auto Parts carries Autolite wire sets, which not to be confused with the spark plugs of the same name, are terrible at best. Autolite plugs are excellent, but whoever supplies the wires for their brand of wire sets definitely isn't up to the same standards. AutoZone's Duralast wires are garbage too. I've had some of them be bad right out of the box.
Motorcraft wires are competitvely priced to most the good aftermarket sets, and are also of excellent quality.
