ive been wondering about this myself too, so whats the best plug for a stage 2 with an intake and exhaust thats going to be the setup ill be using

best copper plug that is

 

most sparkplugs are copper, it is the tip that most people are unsure about.
Iridium tip plugs have the longest wear.. followed by platinum, then nickel
The only real difference is that some plugs out their have nickle cores...
while NGK and most premium brands have copper.....
for longevity an iridium tipped copper core plug would offer you the best overall value....

 

I used the NGK Bkr7e copper plugs and they worked well, but I go a nice boost in perf. with the Denso IK20 Iridium plugs. They work best for my set up.

I used the NGK Bkr7e copper plugs and they worked well, but I got a nice boost in perf. with the Denso IK20 Iridium plugs. They work best for my set up.