If it came with a judy TT... it doesn't mean much.
If warranty says up to 120mm, then 120mm is the max. Although , the 4500 is not a FR bike and increasing the travel will make it feel taller and all, and for an XC bike, that's not always good. 140mm on a hardrock is okay, beucase its frame is probably more aggressive than the 4500s. I wouldn't go over 100mm anyways, I appreciate the low down steering.