Azpkaori

At the moment, I am level 55. I used to play BnS Thailand for quite a while, and I have no problem clearing up to 15 floors with 300ping as a KFM. After leaving the TH server, I moved to NA as a Zen Archer. I still get 300 ping in NA but that's beside the problem. I am not sure if I am undergeared but I can't clear the FIRST floor of Mushin Tower and the bosses seem to burst like crazy and is much tankier than I expected. Did the tower got buffed or has it always been like this? I just need some clarification, because the servers are definitely different.