The NGK Iridium plugs advertise that they increase horsepower and save on gas. Is this True, and are they good for the Maxima.
Also if I switch to copper, what kind of benefits are there? I know the downside, 1/2 the life of platinum. Is copper worth it?

 

Just stick with plats or coppers. I use coppers because I'm cheap and I don't mind changing them. If you don't like changing them then spend the money on the plats. Copper's are NGK BKR5E-11.

 

Terran: Anything better about the coppers?

 

Copper is more conductive so they could potentially have a better spark. In reality you aren't going to gain anything noticeable from them. They are much cheaper though, so like I said unless you really hate changing spark plugs go with the coppers.

 

ngk coppers all the way dont buy those ****in gimmicks

 

I'm currently running NGK Iridium plugs. No gain in power but delivery of power is smoother than the Platinums, never tried the Coppers, so I wouldn't know about those.