Track/s
Having owned Mountain specific sleds in the past (summitx's 146,151), and now have owned 2 SBA's and 11 and now a 13. I have a 14"x2" track on the 13 and love it for riding here in MN. Just can do so many things with it compared to a 136/121 short lug. Just run scratchers on the trail. However I would not go to the Mountains with a 144x2. It still is not a "real" mountain sled IMHO with this track.
If your planing on buying a track any how, with no intention of running it at home, go with the 151 deal. 144x2 is nice and all, but 151x2 is better. I hear ya on the not wanting to strech the tunnel.If any of your buds are bringing real deal mountain sleds, your gonna want a real mountain track, or your gonna be saying woulda shoulda when you get home.
As long as your going all in, make sure you get the right gearing, 20/42 is what the 144x2 assaults run factory. I also would highly consider the Ice age 2 wheel conversion, whats an extra $90 at this point.