NGK spark plug numbers

[Whitster61]

The idea with iridiums is the spark is concentrated to a very fine and extremely durable electrode. They're more resistant to fouling/misfires, and in most cases last the life of the engine.

In a good running engine, there really isn't any seat of pants difference other than your wallet is considerably lighter since they cost 4-5x as much than a regular. But if you want to "set and forget" your plugs go for it.

Autolite makes a very good racing plug, that has a fine wire electrode, like you described. I used to run them, in my old 1979 Suzuki RM400. That bike would gas foul plugs, if you didn't keep it up on the pipe. Once I went to those Autolite racing plugs, the gas fouling stopped. And it just ran better, in general. Those Autolite racing plugs are Much Cheaper than Iridium plugs. I'll bet that they would give every bit as much benefit as the iridium plugs would.