You definitely do not need longer skis. 158s will be fine, you're like 4" shorter than me and I can still rip my old ARVs, which are 165s. If you're not actually hitting huge jumps alot, and spinning them, then you should be fine. It also depends on weight, what you're skiing, etc etc. I don't see why 158 would be too short, but a little more info would help.