This photo demonstrates how most skis present the carbide to the ground, preventing the carbide from helping you turn. This also explains why snowmobilers feel the need to buy longer carbides. The dilemma is that for every inch of carbide added in the front, a useless inch of carbide is added to the rear. Yes, changing from the OEM 3-4" carbide to 6-8" of carbide would make it feel like the sled is now on rails comparatively. Only because snowmobiler's expectations are so low this has become a common practice.
They would have gotten as good, if not better, results if the balance of the skis was correct.
The front of the turning carbide should be off the ground, so the ski is running up-hill enough to maximize the function of the carbide.
To extend the life of the rubber stops reduce the pressure on the shims. This can be done by raising either the front or the rear of the sled.