Many ship lines in this game are out of whack and make no sense, there is no better example then the SS lines.  For KM they recently made some changes to give the higher tiers more damage as you progress however the IJN line is still a mess. Currently the tier 9 ijn does less damage then the tier 7.  Hell the tier 9 has the same number of forward tubes as the tier 5.  There needs to be an advantage for moving to a higher teir.  Currently there is no advantage.  Please fix asap.