Resonator on the 6th Gen

You said you had "the dual exhaust set up". So I take it you have a V6 ? If it is a "true" duel exhaust it comes from the cat with 2 pipes all the way back. It's not just a Y split like a normal duel exhaust is. Is this correct ???
No about the resonator. I the problem with adding one is the fact that now if you add one to make it quieter you loose HP. The resonator is added to a stock exhaust to make it quieter, it also restricts the exhaust flow. That's why it's so loud now. So you going to waste your $$$ on that nice exhaust system if you add a resonator. One thing you can try is putting a "silencer" in the tip of the muffler. It will make it quieter, you will loses a bit of HP, not as much as adding a resonator, but it will be much cheaper to do. It is basically a piece that go's into the tip of the muffler that let's less exhaust out. That's the only thing I can recommend you doing.