I posted a good bit on the denso irridiums - which BTW - my skirt paid for.
I will say this... before I did the weapon r, stage II chip, and remus....
I did the denso irridiums and I felt a difference - not in performance but in how the engine seemed to smooth out a bit. Other people have talked about the same thing and I even think it is on the denso site - and for me - it was true because I am anal. Enough to the point where I installed NGK platinums for two weeks and decided to switch back to Denso's. So when i did the second install, AGAIN, I felt the same thing - the engine idle smoothed out a bit.
KNLNGUS
PS. Denso's are expensive - BUT - when do we have to change them out again... think about that when you contemplate copper - especially when irridium has properties which exceed platinum (which btw - for all out there who adore copper - platinum is better than copper). Not that the NGK platinums and or irridiums don't have copper up in them (haven't researched that) but the tip is the last point where the electrical contact is made with the negative. No carbon buildup vs copper.