Replying to Volkl Shiro Sizing

Usually my rule of thumb for which size of a particular ski I want is, choose the second-largest size available. Whether or not this is actually true, I think this method allows me to see through all the size inconsistencies with rocker, etc. For example: my Atomic Punx are 176, but my ON3P JMOs are 181. Longer ski because of the rocker. Both of these are one size smaller than the largest size available.

SO, I am having issues with this method for the Volkl Shiro. The sizing goes 173, 183, 193, 203. By my method, I would need the 193, but that just SOUNDS too big. Does the Shiro ski shorter than its size number? Or is the 203 just a a massive ski that is proportionally bigger than other skis on the market?

Thanks