I can't garantee a resonator would be better or worse for sound protection vs. a cat. I think your biggest problem is the fact you are running a full 3 with a large amount of horsepower. The best way to reduce your decibles would be to switch to a quieter muffler. I've played with different resonators for a while, but they wont give you the drastic change in decibles or flow that a muffler will. just my two cents.