Spark plug Denso or OEM Mazda

Denso iridium plugs, no more no less and no exceptions.

denso iridium. do them and they’ll be good for another 200k km or more

Denso and Bosch have worked well for us on a 1.6.

Denso itv20 (5339) for stock/mostly stock. ITV22 (5340) step colder if more mods. I have only used itv22 since 2015.

I went with Denso's on my 1.8T because that is what I had on the shelf. but I have ran anything and everything in vehicles over the years, and found that there is not much different between the different types.

As always, go with NGK or Denso plugs.

My car was fitted with Denso Power when new, 11 years ago. It has done 63K Miles (101K Km, way more than the data sheets above say) and the economy continues to improve

I ran Denso iridiums for 100,000 miles on mine, they looked usable when I pulled them. Replaced them with NGK's, no difference in power generated.

the tips of the IKH24s break off in expensive TTRS engines.

I have the 24's, not impressed.