If you realy want to put a good engine in the 400 frame get a YZ426 and put it in the frame. I have heard that it is not to hard to do. That 426 engine makes some power. At the nationals they say that it is going to kick some --- this year.

 

i kinda think that it would be a good idea. you will have an excellent handling bike, with a ton more power. 400's are great but they r slow, banshees haul a$$ but they don't handle worth a $hizit.
and whoever is thinkin 400's and banshee's power r even close to the same is probably about to OD on us, cause u got to be on something good to be talkin like that