Ok, I picked up a very gently used 2006 a while back. Did all the mods. Still found myself chasing some small, yet very annoying problems. I had purchased a YZ exhaust and after putting it on, rejetting, etc, had a huge backfire/pop issue on decel. Also, it seemed the engine braking was way more severe than it should be. Everything I read indicated a lean condition on the pilot. I would check the fuel screw setting and it would indicate that a larger pilot was needed. I would put a larger pilot in and repeat. This went on until I had a 52 pilot in there and it still acted like it wanted more. So, off to the shop. Well, after two weeks, the guy did a basic carb service, checked valves, etc. Compression was very low. He feared piston damage. We talked more about how the bike was running etc and that I just couldn't believe there was a problem with the piston. After our conversation, he decided to rethink things. Well, it ended up being the seal on the carb slide. Bike runs amazing now. No pop on decel. Engine brake is normal. Back down to a 45 pilot, 1 1/4 turns out. If you are in Arizona and need some work done on you bike, contact Rudy at DFR (Mesa, AZ). You won't be disappointed. Plus, he is extremely affordable.