Steve W. gave his recommendation on Rennlist IIRC -- I'd search that up and do what he said.

I assume the stock wires are high quality and will last for a decade or so before they need to be replaced...

I notice we have responses from owners with various year 911s and need to remind that the requirements for spark plug wires depends on the MY you have. The following website (motorcycle) explains it pretty well and is appropriate to early vs late 911s, aka pre and post ECU-equipped vehicles. Notice that in their description, motorcycle spark plug wires are closer to Porsche than regular automotive vehicles:

http://www.motorcycleproject.com/motorcycle/text/plugwiretech.html

"....Cars and motorcycles are thought by many people to be very similar in technology, but in many ways they are not. The two industries have traditionally taken very different approaches to many areas of design and manufacture, and spark suppression is just one example. We have already examined the fact that motorcycle manufacturers (Harley excepted, as with other things) put the resistors on the ends of the spark plug wires. That is, inside the plug caps. They have also always used plain stranded metal wire (stainless steel in Asian motorcycles). That is, good old-fashioned electrically conductive stuff. Car makers on the other hand add the resistor, not in the plug cap, but in the wire, by making the wire itself resistive, i.e. "suppressive." (Sounds like a dictatorial regime, doesn't it?) The wire is not really wire at all, but a mixture of carbon and fibreglas. It is therefore very resistive. Unfortunately, it is also, due to the materials from which it is made, very subject to deterioration and very difficult to make good electrical connections with. This is why the car world replaces spark plug wires very frequently.

Aftermarket Spark Plug Wires
But you don’t ever need to replace the spark plug wires on Asian bikes, unless they are broken or badly corroded. (Harleys and the odd Euro bike are excepted because, like cars, they have resistive wires, not caps.) You should however unscrew the spark plug caps occasionally and do two things. First, resistance-test the caps. Pre-1990 systems should generally ohm under 5k while a few of the later ones will be 15k. Check the manual. Second, occasionally trim a little of the spark plug wire off the end so that the cap has fresh surface to bite on when reinstalled. If you do replace the wires due to their being too short or because of breakage, be careful. It has become very difficult in recent years to find good spark plug wire. Most of the wire sets sold for bikes are simply repackaged auto wire kits, containing automotive type suppressive wire. The stuff is junk, no matter how nicely colored, because it is made of non-wire material. You also don’t need to add any more resistance to the system. So keep that stuff away from your bike. Ask your local motorcycle shop to order it, not from automotive companies, but from Parts Unlimited and a few other suppliers. You can also go to a good old fashioned auto parts store and ask for Delco brand Packard 440 spark plug wire, which is 7mm, copper wire used on cars in the 1950s. It comes on a 100 ft. roll, part number 1851208. Either of these is very close to what the Asian manufacturers used stock. You then attach old-fashioned non-resistor automotive terminals and covers, and you’re done."

Sherwood

Interesting Sherwood...

So, if I don't have EMI issue with the no-name-brand, unknown age wires I have, I can safely go with the el cheapo plain-jane, good ol' copper wires that is on the low end of all brands?

Yes, being an ex-audiophile - how could I hear after been on the track fo decades :), I know there is coper & there is copper... but in this case, its still copper?

I didn't recommend cheap, no-name brand wires. Like the website article, I do suggest copper or metal-core wires for those vehicles w/o EMI issues. Name brands aren't that expensive in bulk. I've used stainless steel-core, silicone jacketed plug wires on my engine for umpteen years. Like the article says, the metal conductor will last forever as opposed to carbon core wire. The insulator may not last as long, but that's relatively easy to observe and test.

Sherwood

Arent you also saying Sherwood that once again the factory did there homework and the factory wires are probably often better than even high end aftermarket?

Yes - I hear ya, just being a little fictitious about the cheapest wires but it is true that more/most expensive models tend to be carbon/fibreglass core, which the article suggests is not good for us.

Hobieboy,
Ficitious understood.

I can't say the factory wires are better since I haven't had a chance (or the need) to use them or purchase the latest aftermarket (equivalents) which seem to be all resistance-type wiring. However, PAG did choose the correct conductor and allowed the spark plug connectors with built-in resistance to do the job for RFI. This combination was better for longevity considering the resistance wire technology of the time.

My original factory metal core wires contracted rigor mortis a few years after Hans installed them. I'm not a forensic scientist, but I'd say the early insulation was more natural rubber than modern EPDM or whatever they currently use. I replaced them with some ss core, super flexible, orange silicone jacketed wire, and that's only the second set on the engine since I got it 30+ years ago. Still seems to be fine, although my car isn't as fast as I'd like. :-)

I also understand the added expense to manufacture resistance-core, spiral wound spark plug conductors. If your car has ECUs and other sensitive electronic processors, you should probably continue using them. However, I haven't seen any A-B tests comparing the two types of plug wire/plug connectors types and their effect on a modern or semi-modern engine. Thus, I have to take the engineers' word for it.

Since I have an early, non-ECU vehicle, except for some Crane ignition boxes, I'm not as motivated to look for the best of the latest type of spark plug wire, but I don't think there's a lot of difference between brand X and brand Y premium-priced wires except for maybe how they install the connectors onto the wire ends and/or the quality of the connectors, or how well the rubber plug fits onto the air shroud opening so cooling air stays contained within. And that's assuming there is any substantial performance difference between premium-priced and the not-so-premium-priced wires.

Sherwood

patrick.. I have a bunch of MSd bulk wire here that I could send up with the BOV

Hey Ben, that would be great... will email you re: details.

thanks!

This brings up a question for those of us running hybrid systems. What combination of wire components to run on an EDIS system retrofit. I had planned to use the Ford wires with Porsche sparkplug caps but that would place suppressive wires with a suppressive cap.
The need to keep RFI down is especially critical for those of us with crank-pulley triggered ignitions/EFI as the VR sensor wires cross the paths of at least 3 wires unlike the 3.2 and later MOTEC with flywheel sensors on the front of the engine.
What is the best system? Suppressive wires or an OEM like setup relying on VR cable shielding, metal core wires, and the cap resistors.

sub'd for future

Since I started this thread, I should report on what I ended up doing...

I switched from my "no name brand, nice looking yellow 7mm bulk wire + old no name brand black generic ones to MSD Superconductor from Ben.

The wiring is a lot neater now but I honestly can't tell there is any difference. But then, I had been tuning my EFI "non-stop"...