There were big debates of this over at freshalloy.com… They say copper makes more power but doesnt last long. Platium lasts long but doesnt make the power. Iridium lasts long and makes power but is expensive as hell. So what type do you run?
I just ordered NGK Iridiums
which one is the cheapest NGK that is 1.99 a piece im guessin copper?
Yea, coppers are the cheap ones. Iridiums are around $10 bucks a piece.
i run iridiums… they come stock in teh vw
denso iridiums here
the ngk iridiums are only $6 a piece, denso’s are $10
x2
Bosch Platinums because they’re cheap and I drive a Prizm…
i got ngk r’s i bought new and planned on using them till i notice my fe3’ motor had iridiums in it! so who knows which i ll use
awsfa-12c motorcraft plugs… $1.67 from my club dealer
hehehe ever price iridiums for a RX7? try 35 a piece
platinums are around 15
i think ill stick to my coppers that get me 5K miles out of a set
Bosch Platinum +4 $3.99 and garunteed for 100K miles 
I do however trade them in once a year and get new ones for free…
these plugs love the upper RpMs :itr41:
no secret to plugs unless you use race gass. lead eats platinuim plugs ,copper will last longer with race gas.no one has ever dynoed more hp in 99 cent plugs to $35 ones. its what your car likes and personal preference.
btw
plat+2s in the gtp
ac commercial grade in the ty
ac reg in the buick
stock plats in the z28
used bosch +4 and have +2 in now… didn’t notice a difference probably going to denso iridium next change
AC delco…
AC delco… what? platinum, copper, iridium?
copper
Iridium - Denso IK-20’s - around 10 bux a piece
On a metal note:
Copper is more than likely to retain the heat and sometimes cause issues with detonation, there was a huge fight on this on twinturbo.net.
I think at one point someone rigged up something to test them and the copper plug was hotter by like 15 degrees at the tip.
bosh plat + 4s
NGK’s