I'm 5'7 and ski a 176. Don't even think about the 171. Personally, I like a longer stable ski, in saying that I will defiantly go with a 181 next time. You should go with the 181. 176 is probably still on the shorter side for you.
The BootBang Collective
"Trying to pick out a freestyle skier by the description of "baggy clothes" is like trying to find a white person in Compton"- 207$
West Coast, New Zealand