not sure if im reading your post correct but the gist i got was
your Denso iridium plugs part no IK24........
the standard Oem equivelent Denso Plug is a Ik20 part number
etc etc
i believe my bosche ones are the equivalent to oem spec
where abouts did you pick yours up john. if theyre fine on yourd im sure they will fine on mine, or would you say maybe 1 heat setting higher than your densos would be about right. maybe a set of Ik22 would be a decent buy for me since i am running around 100Hp less than you
although both our turbos will be stretched to the safe limit.
this is a quote from JKM website
Colder spark plugs remove heat quicker, helping to reduced timing pull
that cant be a bad thing to be honest