Definately first or second plateu for the first time. Most people I've talked to who tripped higher than that really were overwhelmed, and one kid's paranoid mom took him to the ER because he was robo walking like a bad eighties dancer and could barely talk. My first DXM experience was in school with eight Coricidin (240 mg DXM, 32 mgs CPM <-- very dangerous additive) and it was awesome. 270-300 sounds about right. Good luck.