Would they be bad for your sled? No. But i wouldn't buy any either. Don't waste your money. I work at Napa and lots of people ask about them for their cars, and in our opinion don't improve performance in most vehicles. I tried them in my car and ended up returning them. The only vehicles that i know of that actually notice an improvement are in European sports sedans, like BMW cars, where the Bosch +4 Platinum work very well.
I have noticed, however, that some plugs will provide more resistance to plug fouling than others, and that is with the BR9EV or similar fine-wire tipped plugs. But they don't improve performance, just less fouling. But they are also $12 plugs. Irridium plugs work too, but once again, are not worth buying IMO. ES - series plugs work the best for most people, and best of all they are the cheapest to buy. Change them at least once a season or more. Don't buy platinum plugs for a snowmobile, it's unnecessary, as most people will not use the same plugs for years on end. I'd hope not.
I second what Mega Man said. They do resist fouling better than the ES series plugs. I had a motocross bike that would foul plugs every time it was damp out. The only plugs that worked are the splitfire and NGK racing plugs. But the NGK's are over $10.00 a plug. I think if fouling is a problem and your sled is tuned in, then the extra $1.45 a plug is worth it.
This may be true, but if your running the recomended plug and your sled is still fouling, the real answer is to find why its fouling and fix the problem. Whether its carbs being out of sync, throttle or choke cables needing to be adjusted, or the needle n seats leaking.....running a hotter than recomended plug isn't the answer. Fix the real problem, and you'll be happier and safer in the long run.
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