Magnetraction is more for icy and groomed conditions more than powder. I'm not saying you can't ride pow with them, I'm just saying thats not really what they're designed for. If you want a park ski that can rip pow too, go with the Anthem. Same ButterZone as the Invader + wider waist for better pow sessions. JMO though.
i think u would like a longer ski much more, and it won't be too small when u grow. it'll take a few days to get used to the length but it'll be more stable and will help a lot in powder. so yea i'd say 161 anthems.
ok they seem good. just one more question... do you think it will be harder to butter with the 161's cause the butter zone will be farther away from me?