Spark plugs. Why is it so hard?
I wouldn’t argue any of that. My thinking is plugs are cheap. I still am not sold that other than the fact that the center electrode is a fine wire that the fine wire plug does any better at firing than a copper electrode. Even in the link Bewy posted the author never really developed any thoughts that I haven’t heard before, and that is the life span of these plugs is better. I’m still in the camp that if you can get to your plugs the copper electrode is better. I think that some wear of the center and ground electrodes makes firing the gap much easier and more consistent up to the point they increase the gap so far the ignition can’t keep up. I think this is a case of the technology adapted by the OEM’s doesn’t always translate to what people on a forum like this do. I also appreciate your comments on plug wires. I’ve spent a lot of money on plug wires with very low resistance and they were not half as good as some plug wires that had more resistance. It’s marketing hype for sure.
If you like changing plugs, coppers can work. Or if things get changed frequently, then coppers make sense.
There's no drawbacks (other than cost) to the exotic plugs. They last longer, self-clean better, resist fouling and perform better under boost, under higher pressures, at high rpms, and do so without having to resort to higher powered coils (which just burn out coppers faster). When higher powered coils are already in-use, the exotics don't wear as fast and keep performing at their best for much longer than a copper will - because they don't need to tax themselves to death in order to function well.
It's also possible to use exotics to get even more out any ignition system by allowing the plug to see as much current as possible in order to run a larger gap and a hotter spark for more reliable or faster ignition. Changing plugs and coils won't make a well running car go faster (unless the ignition is already junk) but a well designed ignition is necessary to make big-cammed, high-compression, high-revving engines run well.
With all that said: OPs question was about what to use for his combo. He's running EFI with a hyper-spark in aluminum TF heads. I'm running similar (FiTech with computer timing, MSD blaster 2 coil, TF heads on a SBM) and what worked for me is what I described above: I ran the Autolite copper plugs to get my tune (ignition and fuel) dialed in closely with a focus on timing. Then switched to Autolite XP3924 iridiums and opened my gaps from .035 to .045. Since then, things have remained stable and worked flawlessly. Plugs look good when visually inspected and show less soot and absolutely no wear. The copper plugs had rounded electrode edges (soft, not spherical) with only about 500 miles on them.
If the plugs are an issue in the tune they'll show it. Pull and inspect them often. If they're fouling, burning up, or failing with little use then a change may be warranted. If it won't run with the recommended plugs it's likely because the ignition system is not a good match. That's unlikely to be an issue unless adapting some other OEM ignition system onto the engine though.
Just my $.02 - worth the price paid.
