NGK (6619) LFR6AIX-11 Iridium IX Spark Plug, Pack of 1

so far so good... being a plug, i can't describe how much better they are then the last ones i had. These are 1 step better than the stock NGK plug for my Subaru STI. the car already had the Iridium Lasers in it, which are the top of the line plug, but due to the blow off valve, it loaded them up with carbon, so i figured it was time to change them.
so far so good.

This was the EOM replacement plug for my wife's Honda and with 107,000 miles on the OEM plugs, I think they could have
been cleaned and reinstalled. I put a K&N filter in conjuntion with these new plugs and my keeps telling me how much
better her car is running and the mileage has gone up too. These plugs are not cheap but, I truly think you are getting
your monies worth.

These seem to be decent quality plugs at about 1/2 the cost of the "OEM" ones for my WRX, also NGK brand plugs. I picked these out based on the NGK website's specification. Not much else to say about them, other than that they seem to be adequate. I've only put about 1k miles on them so far. The only difference between these and the OEM NGKs (for my '06 WRX) is the tapered tip and the unfortunate discrepancy in factory-set spark gap (see below.)

Warning to WRX owners: I had to re-gap these plugs because they came with a nominal gap of 0.40", not 0.30" that I had assumed based on the info I found on the NGK website. That's why I knocked the rating down a bit - because they weren't gapped as the NGK website seems to imply.

Re-gapping was a buzzkill because the amount of bend required left the tops of the plugs more curved than the factory-gapping. I won't be too surprised if I have to pull them and either replace or re-gap them before the factory replacement...Read more