my plugs are ngk bkr8e ix. general rule of thumb is 1 step colder for every 100 hp but when i ran 15 psi i made 350 rwhp (about 170 rwhp more than stock) and had no detonation issues until i hit 16 psi or above. if the plug is too cold you will have start up issues though.
the plug part from ngk is bkr8e and if you want iridiums you add an "ix" to the end. i have a set of bpr8e2 plugs i would be more than willing to part with seeing as i am broke and in college!
Thanks Andrew but just ordered a set from Todd. I hate how everything seems to be sooo much cheaper and more readily available in the states.
Back on topic, i know everyone says use stock plugs in na bmw motors cause i've seen so many complaints about the platinum plugs and such. However i've also heard that iridium plugs are better for boost applications. Now the plugs i'm getting from Todd aren't iridium but i'm still curious do FI m30 guys have problems with iridium plugs?
i ran denso's for a while then when i had the motor rebuilt, the mechanic stuck in a set of bosch platinum 4 prong plugs because "well the e60 m5 uses them and that is pretty much a race motor and so is yours." moron! the plugs were misfiring up top because you can't adjust the gap on 4 prong plugs and it still made 400 rwhp. but now i use the ngk iridiums. my tuner doesn't like them but his dad (also my tuner) recommended them and they have worked fine for me.
