Go with the 450, I had an 06 250r, sold it and got a 07450r the power difference is immense, and the only difference in weight is about 30 pounds. You'll be much happier having the power there.
2007 CR250R and a 2010 CRF450R
101mph
i have an 03 crf450r mostly stock and ive hit 91 and might get about 93
suspension settings and played with the fuel injection again theirs practically no difference between the 09 and 10 crf450r's
Anywhere from 80 to 90 depending on where you r riding and you shouldn't be asking the top speed of a motor cross bike.
No, but it helps
about 90 mph
16.0 mm.
0.024
.006 in. Intake .011 in Exhaust
Around 90 mph.
186 hp