Its a carbed Evo, I think when I get around to it, stock will be the plug to use, or the champion equivalent.

NGK iridiums did work in another foreign bike I had issues with a while back.

 

If your Softail calls for a Harley Davidson 6R12 and says no substitution, what they are saying is no heat range substitution required in normal conditions. If all you are doing is idling around in cold weather or doing 5600RPM in the desert all day the 6R12 will be fine and unless you believe everything you read that split fire and all the other fancy names say. However a spark is a spark and all the fancy plugs will not do any better. If you want to save a few buck your local auto zone has a NGK 3932 DCPR7E that is nothing but a Harley Plug with out the Harley name. In fact they make the same plug and put Harleys Name on it and it goes out there factory back door in unmarked big brown boxes to the main Harley Distributors