Yeah, I have to agree, with these guys, I'm also an instructor, and it sounds like your dad doesn't have a damn clue what he's talking about, just cause he's 'an instructor' doesn't mean he's knowledgeable about choosing skis. 160 is way to short for you, and the people at your mountain/shop sound like morons also...I honestly don't think I've ever heard of anyone 5'8" riding 150s. Completely ludicrous, get something at least 170 unless you enjoy being ridiculed by 13 year old rental shop snowboard gapers for riding snowblades.