IMO- I would stick with what is in it now if it runs properly. I have a 200 Merc and run the NGK plugs that came with it origionally. Tried to switch and run Champions and Motorcraft, both fouled within a mile of the ramp I launched from. Fortunately I always keep my last set in the boat and could switch back. So from that point have stayed with the NGK's. Good Luck!!