My first motocross bike was a KX60. I eventually moved to a KX100 than a 125. After realizing I liked the woods better than the track I got a KDX220. Stock, these bikes are pretty timid. After a Pro Circuit pipe, slightly smaller front sprocket, and carb mods, the KDX was strong. It felt like it had a lot more power than my 125 (of course it had more power lower in the rpms) and the KDX was considerably faster in a straight line than my buddies on their 125's. A few months ago I sold the KDX and am really interested in Yamaha's WRFs. I'm stuck between the 250 and 450. I'm wondering if the WR250F is going to feel weak compared to the KDX and on the same note, is the 450 going to be too much. Also, being 5'8 160 lbs, I'm wondering the the WRFs are going to be too tall? Any opinions appreciated.