Replying to Mounting Question

So i just bought my new 2010 atomic punx. These have been the skis i've really wanted for a while. I like riding the mountain a decent amount of the time, and i know these are fairly park oriented skis. The feedback I have received on these skis indicate that they are still really solid on the mountain, but I also really want to progress in the park this year because I'm a big noobie. My shop told me that for some extra stability on the mountain I should go back a tiny tiny bit, but I'm really iffy because they are a true symmetrical ski and they are supposed to be mounted center. I'm not really sure what to do so maybe you guys can give me some input on whether it will really make a big difference.