i just bought 4 NGK Iridium spark plugs model BKR5EIX-11. haven't installed them yet. i got these from my local motorsport shop. i asked the guy if these were for lancer evolution 8 and he said yes. i hear that the stock heat range for the evo is 7 and i assume that the 5 in the model # means heat range of 5. but people here are saying cooler is better and hotter is bad. so my question is.... IS THIS SAFE!? thanks in advance.

 

You got hosed. You need a 7 heat range on the NGK (maybe a step colder to an 8 if you're really pushing the boost). Not to mention that "-11" means you're gapped around .044" which is almost twice the recommended amount. I find .028" to be just right.

 

so what is the EXACT MODEL NUMBER for NGK spark plugs for lancer evolution?

 

I believe it is BPR7ES.

 

is that for the iridium or for copper?

 

Copper

The OEM plug is NGK's IGR7A-G.