Do you really think the cats are choking down 20 horse? Move up to a bigger cat. Keep in mind, the cat is matched to the exhaust system, so if you are holding back any significant power, it is in the design and diameter of the entire exhaust system, which cannot be blamed on the cat. One good 3" in/out ceramic metal matrix is good for way beyond the horse these motors put out NA. But the pipe on these cars is no where near 3" ID, now is it.
You could probably do a cam and some kind of homemade longtubes, true duals all the way down with an h pipe, and still not outflow the capability of one good quality 3" converter.
If your cat is clogged, then yes it could be dragging some power, but not because it was working properly and holding you back. Cats fail when you have to much raw fuel hitting them, or you do not get them up to operating temp, or both. Has this been happening to you?
It will run with out them, but whats the point? Unless you have a blower or a turbo, you don't need to take the converter off. But if you want to make some carcinogens, go for it.