Some cats have large flanges on them and bolt to a manifold etc, farther out of reach. That kind can't be cut out in any short time period. The ones they go after are right along the bottom, with simple pipes coming out of them.
That one pictured above, that should come out with about three cuts. It looks like it would fit out the left side of that cage. Just cut the pipe next to it on the right, once on the left a few inches from the cage, and snake it out(or another cut to make more room).
Sawzall's do well with thin or small pieces of steel, really thick or large stuff cause problems for the user.