Yes fellers, you ALL are right, little bit offtopic,
but sometimes if you have big cubatures like on a BMW/MOTO GUZZI 1100 or bigger, normal sparkplugs cannot handle a volume which exceeds 500ccm per cylinder.
Then you have a couple of possibilities.
Either you install a twin spark ignition system
or
you take this special sparkplugs from BRISK.
Hard to lay hands on nowadays, but ....
Of course mapping is supposed to be changed too.