Hi I'm in the market for a new bike, been looking at 450f efi bikes. Are these bikes to fast and heavy for a 17 year old 5.9 175 pound? I'm coming off a 2006 yz250f with full fmf exhaust Bondi engine with big bore kit have had it for 3 years. I've been wanting more power but heard 450s,are crazy, and not to sure about the weight of them compare to a 250f. I ride open fields, trails, and go to motocross tracks 10 times a year. Would like to hear everyone's thoughts. Thanks.