Gates
I ran a Gates Extreme on my Exciter SX and it came apart. Replaced it under warranty and after the season was over my primary sheeves had a groove worn into them. I'd never use anything other than Genuine Yamaha on my sled again. The OE belt works great why would you want to use anything else? The 8DN is good for at least 5,000 miles, in fact the one I'm using this season has more than that already and is still in specs, my sheeves are still near perfect too after 15,500 miles.