Yeah, yeah, yeah, we're tired of the television commercial featuring James Stewart riding and talking backwards. We're even a litle tired of James Stewart, who nowadays seems to care more about his reality-TV show, Bubba's World, than his racing career. But we're not tired of the bike Bubba is pimping. Never mind the inevitable comparisons to the late, ill-fated Cannondale or the similarly revolutionary Husaberg, Yamaha was the first major manufacturer to design a clean-sheet motocrosser since it sprang the groundbreaking four-stroke YZ400F on us back in '98. The 2010 YZ450F is not only the Tuning Fork Company's first MXer with EFI (tunable at that), it's also got a unique engine layout with a rearward-sloping cylinder, forward-facing intake and a Tornado exhaust that spirals around under the seat (the airbox is up in front of the tank). The resultant mass centralization makes the bike more stable and feel much lighter than it is. One appreciates that at the end of a long moto.