I got done building my 09 trx400x at the beginning of this month and it is really fast now. It is bored to 416 with a 10.8:1 je piston and a stage 1 hotcam. It also has kibblewhite valve springs and a crf450 timing chain. It has about 30 hours on it and 10 of those were break in. I recently drag raced a raptor 700 and some 450's and won. I would like to see more people create 416's that will compete with 450's.