[JLL]

I've also seen a couple threads on copper plugs, but haven't seen much info as to the best plug which may last longer and provide the best performance at both high AND low end grunt.

Is the engine stock or modified (tune, mechanical modifications, ect)?

If it's stock, use the OEM plug, the best quality fuel available, and keep up religiously on your fuel/induction system maintenance. There isn't much you can do with a stock engine to make it better than GM did.

If the engine is modified that is a different story.

 

[JLL]

There are always ways to improve from the factory, since factories need to meet price points. This means that using things like cheap copper plugs saves money and generates a source of revenue for the dealership.

Copper spark plugs from the factory? I can believe we're only 2 1/2 months away from 1993. Sorry, but that made me laugh. I'm not aware of any modern automotive engine that uses cheap copper spark plugs from the factory.

The other thing is that iridium plugs were not that great for high boost applications in the past, since the engine was originally designed in the 2000s; copper plugs were often used for turbo applications due to fouling and the lack of reliability of iridum.

I agree. I use non-resistor "copper" spark plugs. But the OP was asking about "longevity and more low end grunt" which a "copper" plug will not achieve better longevity.

Now that there is Ruthenium HX built specifically for turbo applications; that is no longer a problem. I ran copper in turbo cars until recently for this reason. However Ruthenium is legit and definitely an upgrade over stock.

I tried them and I couldn't see a difference. But your results may vary.