This is from Magnecor's website:
"Ignition wires with grounded braided metal sleeves over the cable have come and gone all over the world for (at least) the last 30 years, and similar wires were used over 20 years ago by a few car makers to solve cross-firing problems on early fuel injected engines and RFI problems on fiberglass bodied cars — only to find other problems were created. The recent Circle Track Magazine (USA, May, 1996 issue) test showed Nology "HotWires" produced no additional horsepower (the test actually showed a 10 horsepower decrease when compared to stock carbon conductor wires).
It is common knowledge amongst automotive electrical engineers that it is unwise to use ignition wires fitted with grounded braided metal sleeves fitted over ignition cable jackets on an automobile engine. This type of ignition wires forces its cable jackets to become an unsuitable dielectric for a crude capacitor (effect) between the conductor and the braided metal sleeves. While the wires function normally when first fitted, the cable jackets soon break down as a dielectric, and progressively more spark energy is induced from the conductors (though the cable jackets) into the grounded metal sleeves, causing the ignition coil to unnecessarily output more energy to fire both the spark plug gaps and the additional energy lost via the braided metal sleeves. Often this situation leads to ignition coil and control unit overload failures. It should be noted that it is dangerous to use these wires if not grounded to the engine, as the grounding straps will be alive with thousands of volts wanting to ground-out to anything (or body) nearby."
IMO, you 'd be better off getting a set of quality wires such as Jacobs or Magnecor. Plug wires are not going to add additional power, but will restore power lost gradually over a period of time.