i'll agree. you're going to beef up a bit over the next year or so. the 171s would be good for about a season, maybe less, but if you're already at least a little comfortable in the park, the 178s will be perfect. as one of the guys said earlier, with a center mount and a super soft tip and tail, they ski short.
Hope this helps.
08/09 Anthems
http://www.sierrasnowboard.com/Line-Anthem-Skis-41855.asp
EP Octolands
http://www.sierrasnowboard.com/2009-Line-Anthem-LTD-Octoland-44913.a