Like you, I wanted the benefit of a freer-flowing exhaust, without the noise. Originally I wanted to have welded-in performance cats, but found that it couldn't be done. I went with the Motordyne ART pipes, and included some observations in this thread:
HFC fitment...2.5" or 3"?
Now that there are some miles on the exhaust, as the installer suggested, the insides of the new pipes have lined with enough soot to deaden the sound even further. The Garageline X and Mid-pipe combo does add some low-end grumble through the floor, but it's really not that bad.
In my opinion, if you want a quiet-running car, keep the stock muffler (perhaps upgrade to a Nismo), and go with the setup I've done.