Here's a helpful thread, guys to seem to run either plug... http://www.buellxb.com/forum/showthr...-Iridium-plugs
When running NGK you have to make sure they are gapped correctly too.
My advice to you is to pick up the OEM plugs from your local Harley dealer. Eliminate all the guess work and run what Erik sold you the bike with: perfect gap, depth and heat range....