I have a friend that has a 400ex and he says he takes it through pretty good mud can they go through a lot of mud i dont know very much about these atvs but i didnt think they were really made for that he also has a warrior and says the same things about it he also says they can tackle some pretty steep hills is this true which one is better for this

 

the 400ex is the best by far

 

honestly I can say that both quads would not be very good in mud, they both only have about 4 inches ground clearance. My 400ex gets stuck easily, you can have all the power in the world but your not getting through the mud unless your tires are catching traction. Plain and simple the two quads have to little ground clearance in the back to be any good in mud. As for hills they could both climb hills very well, (the ex can very well anyways, I've never seen a warrior climb a hill). The EX might climb better because it has more power and it's lighter.