Spark plug NGK or Motorcraft

first set i used were NGK R5671A-7 non-resistor plugs gapped at .025\" had ran multiple sets of these for well over 20k miles with zero issues.

I have now used those plugs of mine up to 35psi so far with no issues.

Same exact plugs I use they haven't given me any issues I have em gapped to .022 and no misfires at 31psi, the car made over 600whp with no problems with these plugs, and they cost about $3 a plug.

DCPR8E NGK copper. we use stock gap and change every 10k-15K miles. So far so good for me. 12psi fyi.

I still use stock gap on my DCPR9EIX on my turbo R with no missfires.

Running NGK DCPR9EIX gapped to .022" with no misfire issues.

The 9s are good. Considering I have run them anywhere from 15psi to 36psi of boost and they have performed flawlessly I would say that they work well.

I replaced the spark plugs earlier. The new spark plugs is NGK PFR6Q from Checkers. It is gap @ .032. The old spark plugs are the very cheap Autolite. The previous owner probably tried to save money, but it end up cause me a lot of trouble. The gap of Autolite plugs are more like .042. I drove it a couple blocks I installed the NGK, and it felt better.

Napa usualy is the only parts store around me that carries NGK in stock

I just did mine not too long ago and bought the NGK's @ Advanced but they claimed that it had to be gapped @ 0.032 but when I took the old ones out, the bosch we gapped @ 0.030. I put the new ones in and you can feel it not running as smooth but I've been too lazy to find some gapped @ 0.030.