exc means "Enduro and Cross Country". they mx version is called SX.
the bike is outstanding for enduro. if i find one with plate at the right price i will buy one.
they are good bikes, only they tolerances seems to not be the best on older bikes. the more extreme case i know is the ktm 360 exc and 380 cylinders, have poorly mismached ports. the two side ports on one cylinder have 1,5 mm difference in height, the other cylinder have 1mm tranfers difference between right and left ports.
out of the crate they are better bikes for slow/woods riding than any japanese bike