I had a Blaster with a pipe silencer filter rad valve jetting and it smoked my friend's 250ex that had a pipe filter carb and cam.

 

The 250 ex is not a drag racer by any means, the blaster will be faster, just the fact that the 250ex ALMOST keeps up hauling a much better built chasis, reverse, centrifical clutch, shaft drive, etc etc AND its a four strock with only 50cc less!!! says more than enough to prove its a much more quality machine, I have owned them both and the 250ex is a bike to keep for life for kids and grown ups of all ages to have fun with, while the blaster was fun for about 6 months, a great begginer machine to lead to bigger and better things, but hardly a keeper.
Just some opinions
Jetjock16