In preparation for a 70 mile hare scarmble this last Sunday I decided to set the cam timing to YZ specs. I don't want to exaggerate this out of proportion but it was incredible. The punch in the midrange brings it closer to the feel of a 2-stroke. This was extremely useful pulling out of tight corners in deep sand washes. As for the down side, I didn't see any in performance. The first half of the 35 mile loop was very technical with the hardest being a 400 foot assecent up a rock fill canyon. I was still able to lug it in 2nd and 3rd without any noticable loss of lowend from before to conquer these types of obsticles. I feel bad for the guys of similar riding abilities that had to deal with the point and shoot power bans of the 2-stokes. I give this mod two thumbs up and would never consider switching back! The only down side was the bearing retainer clip. I stuffed the timing cavity with paper towels and still managed to drop it inside the engine . Fortunately it came right out with a telescopic magnet .