Ok. So I promised ya some legit measurements and mounting advice once I got mine in my hands and were able to accurately measure them myself. I should say that it's a good thing I did so and didn't go off of my buddies measurements because they were off. Plus the running surface IS actually symmetrical although the rise is a touch more dramatic in the tips, creating an optical illusion, which caused me to think there was less running surface is the tips compared to the tails. So let's get on with it. I am basing this off of the 178s. As posted by someone above, the midsole line is actually at -2.5 back from dead center. Also on a flat surface I was able to measure the running surface contact points. 30 on both the tip and tail so it is a symmetrical running surface. Now that doesn't mean that your running surface is only 118. The rise beyond 118 is minute for quite a bit so on anything other than an absolute sheet of ice, it's going to be more like 138 for groomers and 170ish in anything over an inch of fresh. So what does this mean for mounting? Well it becomes a preference thing at this point. Though I believe that a dead center mount will hurt turn initiation due to the asymmetrical sidecut. The tips are 140 at their widest point and the tails are 136 at their widest point. So you have a difference of 4 but you half that because you can't be on both edges at once and you end up with 2. So at this point I would say -2 from dead center is going to be your optimal mount IF and only IF you plan on using this ski for bigger park features, backcountry booters, and generally more groomers than fresh. IF however you plan to use this ski for tree runs, pow, etc....I would recommend mounting at the midsole line at -2.5. It's going to be a tough toss up because normally a .5 difference isn't that dramatic. Especially on a fairly symmetrical ski. However, it is my opinion that mounting further forward than -2 will dramatically alter your turn initiation, making it more difficult, and will alter your turn exit, causing you to "wash out the tails" under hard stress. All of this is just my opinion based on my own measurements and I encourage you to do the same. I will say that I will likely mount mine at -2 but I intend to use mine as a general all mountain jibber and pull out my opus for the deep days. If this were my "quiver of one", I would mount -2.5. Hope that helps and good luck with em.