I'm around 168 but I'm going to say I'm 170 because I have terrible posture and when  I got my license done 2 years ago at 17 I was 170 barefoot. I want to get 5.08cm done so I can reach 5'9" but my arm span is 170cm. How bad is it to have a shorter arm span? I could maybe put on an extra 2cm to my wingspan working out my shouldersa and back  if I were to hit the gym.