you are definately right the new EXC and SX are the new ones 06 - ...
and they are 525
Previous years 02-05 the EXC and the SX wore 520. but i don't see the difference the 520 is 523cc and the 525 is 525 cc (think the ktm guys are jokers, but they do produce extreme good bikes)
About the KX how is that for a ride? is it bad or just fancy a new one?
I've driven a KX 500 from the mid eighties, found it similar to the CR 500, so bloody fast.
Drove the KTM yesterday and today, damn it's fast, first time I opened the trottle completely I thought i was going fall of, my arms still hurt, but hey that's why I do it.