I am 5ft 9in and weigh 145lbs 15 years old ski very very very aggressive. i ski about 30% park 40%all mtn, 30% pow. I already own a piar of 07-08 surface watch lifes in a 173, i need to get a powder/charging ski. i found a pair of last years salomon guns for cheap.they have them in a 174 and 188. i am not sure which size to get. please give me your opinion