This conversation is on-going in another thread.
But, here's my personal -first hand experience with a 496HO and plugs.
First of all, in mine, I changed a few seasons ago to Denso Irridiums. I was having a surging (at idle) issue and it helped smooth it out. It ended up being a bad TPS, but at least I knew I had good plugs!
Anyway, some friends have a 2003 Shockwave with an H-O. Every trip or two out to a lake would result in popping and sputtering. We drained fuel, ran different brands, ran multiple brands of injector cleaner, everything. AC plugs, Autolite plugs. Each set of plugs would run great for a few hours - maybe five total- and then start sputtering again.
I checked the fuel pressure, just to see if maybe the regulator went bad and it was running too high. 43 on the nose. Wires all checked good. No codes in the ECM. The plugs were getting fuel-fouled. My theory is, they still have the turbulators in (afraid to pull them out

sphss) AND it has permanent mufflers. The total restriction in the exhaust is not helping the already rich fuel setup that these motors have (nasty transoms).
Anyway, I suggested putting in a set of the new E3 plugs. They dyno well and have a visually larger spark. So, in they go. They are well over 10 hours now on this set of plugs and not one sputter. They might even be pushing 20 hours now, as they have been running the boat all this week. Still no sputter/popping.
I am sure Irridiums would work just as well for this situation, but I definitely know the E3s have worked.