How can you tell if your cat is plugged? My v6 is kinda slow revving and seems low on power?

Take your vehicle to a muffler shop. They can test the cat. converter by drilling a couple holes (which can be plugger later) and making a pressure test. They can tell you pretty quickly if your cat is plugged. When mine plugged, I was barely able to pull away from a red light. You lose most of your ability to accelerate. Same as plugging your exhaust pipe.

You can also try removing your o2 sensor and doing a pressure test there.