Just got an 09 teryx. Had to have at least an 09, since my buddies 08 backfires during engine breaking and I ragged him for it. Horrified when my new/used 09 backfired worse than his. Took a beating from the guys. I read some posts and decided to find the problem and fix it. Turns out it was a loose header bolt and a burnt gasket on the dragonfire pipe. Installed new gasket and the backfiring went away. Thanks for the posts. I hope this helps someone else.