I've got an 02 Raptor that has recently developed a backfire when I shut it off. It doesn't do it all the time but probably 70%. Sometimes it's not to bad, other times it sounds like it's gonna blow the exhaust off. To me it sounds like it's burning fuel out through the exhaust so I'm guessing exhaust valves maybe? Any insight would be great.

Also I was looking at maybe doing some internal engine work but I'm not sure what would be best for my type of riding. I ride dunes 100% of the time and am fairly aggressive. I'm more into treeshots and hill climbs than drag racing. I love the trails too but my main concern is having the power to turn at any point on a hill and come back up. I dropped a tooth off the front sprocket and it helped but I'd like it to wind out faster and be able to pull third gear for the extra wheel spin. I've got a Yoshi pipe, K&N, jetted, and 20x10x10 9 paddle Hauler extremes. I was thinking maybe just a mild port or a cam but I'm not sure if that would be what I'm looking for. Maybe a higher comp. piston or would it just be better to have it all done and not worry about it?