unless you will be landing switch in pow, mount them an inch behind the classic mount. I mounted mine dead on the classic mount line and I have to lean back a little to keep the tips up alot of the time.
if you got the 81s i mounted them 3 cm back from dead center. good for forward and backward. ski is so sick in the bc for hitting booters and slashing turns.
I had my thugs center mounted earlier this season, but I got them mounted back, and even that isn't enough. Ive got the 181s, knowing what I know now I would've gone for the 190s.
I'm 5'8", and I ski race, its weird skiing big mountain on something shorter than a GS ski. 181 would be fine for park, and trees, but for big mountain, and straight lining chutes, something longer would be nice.