You only need one cam, the intake cam. Get a crower victory cam and retard the exhaust. And it IS a YAMAHA so reliabilty is already an issue. Don't go big bore for trail riding, you'll melt the piston to the cylinder, if you havent already noticed, they kinda get a little hot anyway. Less cylinder space equals less heat resistance wich equals meltdown. Go with a 13.1 piston, crower victory intake cam, retard the exhaust, FCI intake and a full exhaust..... better yet, don't get the 13.1 if your trail riding, race gas is too high to waste away. Maybe a 12.5 is what you need.