Replying to 189 or 179

im thinkin right now about wheather i want to get a 189 pistols(or somethin similar at that height)or a 179 pistol or somethin simialar. i never ride park, mainly big mountain and stuff like that.not to many man made jumps in my style. im like 5'9 which is 180cm. so i could go with a ski exactly even with me, or 10 cm taller. i think i might grow some more, doctor said possibly 6 foot, but iv still yet to see that come along. any suggestions.