My NGK Irridium 7s are fouled after a few months of use. They were quite expensive and are now in need of replacing. There has been no performance loss yet, but the bigger area that encases the needle-like center electrode is gone on my plugs. I don't know if this could be caused by running extremely rich for a period of time, or just from boosting nitrous.

I need a good suggestion on a spark plug that will work for me.

 

most of the time the regular NGK bkr7e will work very well and don't cost much,