I had the ITV20, ran great then had misfire from cylinder 4, replaced faulty coil, then next day misfire in cylinder 2, checked coils and they were good, spark plugs were good too. Didn't know what the problem was, but I decided to get the ITV22 gapped to 0.028 and that fixed the misfire. (Note: I am stock except for hpfp internals). These are great plugs.

I normally use NGK Spark Plugs for my Mazdaspeed 6, but didnt like the price I paid for them here in New Zealand.



I decided to go for these Denso Plugs, due to the fact that im paying less per plug including shipping, than I did with NGK.



This is the best decision I have ever made on Spark Plugs. My engine is less hesitant than when running NGK plugs, there is also a slight missfire with the NGK plugs. With these Denso Plugs there is no missfire. I will definitely be using these plugs in the future.