Well something is certainly different, we've got a couple of 13's in our group, and 11's and 12's. The 13's are definetly outperforming the rest, out of the box, (original box)all things equal. Comparatively to other sleds we ride all the time with, the 12 XP was usually faster than the 11-12 Pro, same XP won't beat the 13 Pro climbing or on the lake, packed or powder. No Cats with us to compare. Sunday watched a 13 XM 163 race a 13 Pro 163 on lake 8 to 12 inches of new snow, Pro by a bit every time.
So something's different.