I have read in several places that the iridiums are not a good idea for boosted applications. I can not remember the reasoning behind this. I have used the autolite iridiums for some time now with no problems. For my heads I have a limited selection of plugs.
1979 Mustang coupe, EFI 393, A/A intercooled Eaton m122, 4r70w trans, Megasquirt II, T-top swapped in.
1990 Mustang, 545 BBF, C-4 with brake, ladder bars, tunnel ram with two Predator carbs, solid roller cam, 9", 390/45r15 drag radials.