KDXRIDER.NET

Is it possible to really mod a kdx and race really big enduros/hare scrambles, and win? (with an adequate rider) races like erzberg, or romaniacs

I would say yes and especially a KDX/KX hybrid. Just look at what Jeff Fredette did on a KDX for so many years racing ISDE. If your skills and physical conditioning are up to the challenge of those races, there are many ways to coax more power out of the engine, to make the suspension better, and the overall weight lighter (hybrid) to be more competitive. I personally think my bike is capable enough just the rider isn't!