Where to mount my pow skiis?

Just picked up a pair of 182cm shoguns and not sure where to mount them? Definitely going to be landing sw in pow and doing flips and whatnot. Gonna be riding sw pow but dont want to effect my ski like mad hittin cliffs and riding trees. True centre is about 9cm forward of the line and the guy at the shop suggested going with +5cm from the line or -4cm from true center. Will not mounting em true centre make a big difference in swing weight? Will mounting them true centre effect pow riding too much? What you think? ++karma for help