On my AX10 I put on a set of Losi Rock Claws, narrowed and star cut the original foams and it seemed OK but I hated the lumpy tire effect that it gave.

I put a set of memory foams in the other day just to try them out.
I have read a lot of posts on different forums about them and in one forum they said to not cut anything just put them in the way they come so that's what I did. If I need to cut them down later I can always do so.

My impression of them is favorable, even un-cut they really seem to work well. They conform to the rocks really nice and seem to hold the side hill very well.

Just my opinion and I'm sure there are others who have tried them, maybe they will post up their opinions.