I have a 2005 kfx 400 and love it in my opinion it makes great power and handles really nice the suspension on it is awesome and really soaks up the bumps and whoops i weigh like 170ish and its perfect for me i got it mainly because i wanted electric start and reverse,a few thing to look out for with the kfx/z400 2003 had problems with the frame breaking up front,in 2005 they upgraded the suspension on them to shocks with rezzies changed to a bigger carb and diffrent cams for more power to save weight the added alum rear grab and alum front bumper they also started using magnisuium parts in the engine to save weight like the clutch cover, valve cover and they are now having problems with the magnisuium covers corroding from the anitfreeze apprently water dosent sit to well with magnisium so u have to do a 35 dollar evans coolant swap to the quad,or change out your clutch cover to a 03/04 version.
heres some videos ellsion took of us out riding
A all out 4 stroke drag race
http://media.putfile.com/another-drag
Another Drag race
http://media.putfile.com/Drag-race10
Chris642 gets owned by Screaminglilttle2stroke
http://media.putfile.com/chris-gets-smoked
Another Drag
http://media.putfile.com/Chris-trex-screaming
Drag race me, trex and screaming
http://media.putfile.com/jeff-drag
Screaming and Trex
http://media.putfile.com/Trex-scream-drag
heres mine!