Is there something at 16m gsp im missing?

I swear everyone past 16.3m is using some form of mod or something that lets their inputs register hella fast. It feels like my delay is slightly worst than them and I can feel it. I have many hours into smash and I swear I can tell somethings off cuz as soon as i hit 16.2 the gameplay changed. feels like theyre playing offline and im still stuck online.