Spark plug NGK or OEM Mazda

I’d personally run NGK, they have always performed better than Bosch in these generation engines. Iridium if possible and just whatever my reputable local parts supplier would get me.

I'll just start with my bias of never using Denso for anything anymore but for plugs I only use NGK laser iridium and always get at least 80k out of them.

Should have used NGK Laser Iridium plugs and Hitachi coils.

Mazda skyactiv engines are beyond easy to do. Did it on my 16 Mazda6 in 20 minutes. Probably can be done sooner if the spark plugs are pre-gapped and you're not OCD.

Did 3 of the 4 of them on my wife's CX-9 and it took way longer, due to the turbo parts on top and the engine being set, so far back (vertically challenged and T-Rex arms). Dealer ended up doing the 4th one (driver side plug).

Rock Auto has good deals on the NGK plugs, that are basically the same as the OEM ones.

Torque wrench is unnecessary for plugs. I have several and have never once used them for plugs. 1/4 turn past hand tight is all you need. Good plugs like ngk laser iridium or ruthenium hx will run you less than 40 bucks. A small single use packet of anti seize compound and a 6 pack of your preferred beer. Less than 100 bucks all in and an hour of your time.

NGK plugs have instructions on the package and do not require a torque wrench. I have a torque wrench, but I do not use it for my spark plugs. It's just hand tighten until it makes contact - then turn it however many turns they say with your socket to fully seat it (usually like ½ - ¾ turn or something like that).

You don't need a torque wrench, NGK plugs have a crush washer and specify half turn past initial contact. Did my Mazda 3 with no issues. I have a torque wrench and didn't use it.

Went with NGK spark plugs that was bundled with some generic wires and coils, not ideal but it’s all I could afford at the moment

I learned that proper, very hard to tell, NGK knock offs even existed after I was bitten by fake ones off Amazon. The porcelain around the center electrode broke off and went through the engine.

I have installed brand new NGK sparkplugs and Bosh ignition coils...but the cylinder 1 misfire does not move or is resolved at all.