My car is slightly modified , so your result may differ from mine. My OEM Platinums look like toast , i got my moneys worth out of them. But towards there 60k mile life span the car was running a tad sluggish, idle was at 500 rpm and ruff, etc. Instantly after i installed the Iridiums , the idle went back up to 700-800,idle was smooth. Didn't notice to this morning , on the highway mileage went up a few points. 24.9 to 25.4,the acceleration has slightly increased and the responsiveness is now back, and the tone of my exhaust note changed slightly.

Picked them for $8.74 a plug at NAPA compared to the Dealers $12 dollar a plug.
Definitely worth picking up if your about to change your plugs.

 

I have heard from my mechanic that iridiums don't make much of a difference. What he told me was that they might be no good for the car. I was hyped about them myself at one time.

 

I have been using NGK iridiums for almost 2 years with no noticable difference from with OEM double platinums. Also no difference on butt dyno, idle quality, idle speed whatsoever. But no harm to try anyway.

 

I also switched to the NGK iridiums a few months ago. My car has aprox 60k on it and i really noticed no real difference either. However, some people argue they are better than platinum and hey where actually cheaper than hte stock platinums. Unless your plugs are fouled you really shouldnt notice much of a difference between plugs. Iridiums just use a smaller electrode, finer spark so they MAY help ignition life somewhat.

 

Just install mine weeks ago, don't feel any different at all, car at 80k miles.

 

got mine about a month ago car felt alittle better i changed them out at 67000 my stock ones were also toast. i only changed them cause i got nitrous. but i would definately recommend them.

 

IIRC, Iridiums make gains moreso in FI cars but negligible gains (if any) on NA cars. Either way, a new set of coppers > worn plugs of any type.

 

All of the psychology stuff, really

 

So a smooth idle over a ruff one is phsychological, increase in milage is phsycological, even better response is that too......man i love being crazy then.

I rather have that then the latter w/ worn out plugs....

I could see if i said it gave me 15HP or something of that effect. Like i said , your results may vary, we all don't drive the same Maxima's. Some modded, some not, some in good condition, some in fair condition. I can't speak on everybody elses maxima except my own. And those are the changes i felt and seen...