A D8EA is what the motor calls for, going to a hotter plug is not going to benefit you any, a hotter plug would be a D7EA. The only thing its gonna do is make your motor run hotter and could risk burning a hole in the piston. Most of the time a hotter plug is only used on 2 strokes, where it wont stop fouling plugs, the hotter plugs burn more of the oil off faster. It may benefit you, but its kinda risky. Buy a denso iridium replacement plug for it, set the gap right, and you will be set.
It may help it some, im not saying it wont, im not too good around 4 strokes in genral, only a warrior, but the only time i have ever seen anyone go to a hotter plug was when they couldnt stop a 2 stroke from fouling plugs. Try it and gives us a report, but make sure its not running super lean. Maybe you could contact NGK and ask them, i just might do that if i can find a website.