You can remove the resonator, it does lessen the noise a bit, and guys are correct when they say no cats will be illegal. The fact that there are four means that in intelligent states you can safely remove the rear cats.
Ford did not know how or if emissions could be met with one cat per side. They also didn't know that emissions could be met without an air pump, or air injection into the cats. Here we are years later, learning from earlier stupidity.
One high quality cat for each bank is sufficient to reduce the two chemicals being tested for. never mind that other chemicals are created by the cats, chemicals which may be just as dangerous to the environment. No one thinks through these things, a few stupid government officials get together with some tree huggers and make up some crap laws.
Best 302 exhaust, replace it all, headers to tail pipes. Make it dual mufflers, two cats(for the greenies), two tail pipes, 1.625" or larger headers, and at least 3" piping throughout. If you do that, which is the best exhaust, then you will have to retune the PCM. That is too much of a reduction in restriction for the computer to handle. The engine will run lean, and need more fuel. Regards,