Hey buddy, I have a 2001 Yamaha YZ 250 with several tricked out parts... check my sig below for the list that i bought for $2600. Yes, 250 two strokes are very fast, mine is pretty damn deadly too and the other day i almost flipped over in 3rd. and my front end comes up in 4th. no problem so yes they are very dangerous and you should test one first to make sure that you can handle it, it will haul you around, im just turning 15/ 5'9"/ 140 and i dont even think that the bike sences my weight. The rear tire will lose traction and you will have to counter steer in any gear if yours is as fast as mine. Mine is good in the woods as long as you keep it out of the power band but it is a little scary for hard packed surfaces, so keep your foot by the rear brake! No, 250's dont make double the power of a 125 but they do make alot more. Stock for 2004 a 125 is like 32 horse power and a stock 250 is like 47 horse power. If you only ride a Banshee in 3rd. and 4th. dont get a 250 unless you are going to use the power, you might kill your self! I raced a 2002 'Shee w/ FMF Fatties & Power Core2 silencers, K&N filter, 280 Jets, Boost Bottle, and Oversized spider trac rear tire and i beat him by 10 bike lengths and he couldnt reach my top speed. He was a good rider too. I would recommend a 125 at the most if your not gonna be WOT on it all of the time.