Plug wires - Every hot rod nut I knew growing up used to upgrade his wires from stock. Seems like a common thing to do on various racing vehicles, why not an ATV?
Spark plug - not saying it will or won't increase power, but maybe give better fuel mileage and cleaner burn on fuel? I've read some opinions stating the Platinums and Iridiums might better resist fowling?
It was mainly a curiosity question to see if anyone has tried it and did it make a difference. If folks are willing to spend $1k on a tuner and pipes, change from CanAM oil to Amsoil, install uni filters etc.., I just thought someone might have spent $14 on plugs or wires? I agree stock works, but figured I throw it out there.