Splitfire
I've used the ND iridium's and they worked fine but no better than my tried and true NGK's.Either is fine.
As for the pricey RM plug,I had a 99 and the reason for that plug is as follows:
Suzuki spec'd that plug design from NGK for those and later years due to "excess" internal vibration.If you look closely at the top electrode you'll see it doesn't have a sharp 90' bend but rather a rounded profile.It apparently has a stronger attachment point on the base as well.That plug won't give you a bit extra performance,but shouldn't have the top electrode break off and bounce around between your piston and head.
I mentioned this to the guy that bought my RM and he said-I'm not paying that for a stupid plug and laughed at me for doing so.A year later his top electrode broke off,snagged the ring at the exhaust port and wasted the cylinder and piston-tee,hee.
It's pricey but tuned right,you should only go through one plug per year so I wouldn't take the chance-or buy the 1/3 cheaper plug and replace it 3 times as often just to be on the safe side
