Symmetrical as in bit skis are shaped the same or as in the twin tip and rocker? And also Is the ski a park ski or all mtn with a bit of park or soft snow focused?
**This post was edited on Dec 14th 2020 at 2:53:00pm
If you don't have a true twin (most skis aren't anymore) you probably want to be 2cm back. But 1.5cm on a true twin wouldn't be noticable I wouldn't think. Way better than noticing your heel piece ripping out.