I bought a set of the denso iridiums from Opie oils last year at Japfest
Fitted them myself, which isn't as difficult as you may think. I was advised by some people to take the plenum chamber and lower collector off completely, but unless you like the extra work, or you are adding a spacer at the same time, there is absolutely no need.
Take the strut brace and air intake pipe off to start with.
Then move the wiring looms on both sides running above the coil packs out of the way.
Undo the bolts holding the coil packs in place, and pull them out of the way.
Then with a suitable extension and plug socket on your ratchet undo and remove the old spark plugs and replace with the new ones. Do not overtighten A simple nip up is all you need to do.
Refit the coil packs and wiring, then the air intake and strut brace, and Bobs your uncle