Replying to The Right Ski Size?

hey guys, this year i am getting dumonts but im not sure what size....Ive been sking the 166 foils last year and im still only about 5'7". Im a senior in HS and prob not gonna grow much more. But im wondering if i should go with the 171 dumont or the original 176? The 171 is like exactly my height and the 176 is over my head. Im worried with a bit of a longer ski though that skiing rails and switch ups/spinning on will be harder? idk what do you guys think i should do?