Hmm, now that you mentioned it, my K2 uprises came with a gasket/foam thing and I never knew what it was for, and their instruction were shit. I just looked it up and one feature for the Uprises is a
• Harshmellow gasket under the chassis isolates vibration• Reduces rider fatigue• Absorbs harsh landing impact
When I had to adjust my bindings it bothered me a little that it scratched the shit out of my new SL but that lasted all of two seconds because it was going to get beat up anyway. But still I like it to be clean before my first run.
Now I know, I have to cut out those two gaskets hopefully I didn't throw them away. Plus they add additional dampening which isn't too bad.