I've had a few different setups now.
My libby is the 3.7l, if it makes a difference.
Started with the stock muffler, just added a tip to the end of the pipe (was mainly for looks), only noticeable when the car was started, besides that, nothing.
Next was a Flowmaster Super 44. Was much louder at startup, a nice low rumble. Bad drone on the highway, I had no problem with it but my family members found it to be extremely disruptive.
About 4 months after installing said flowmaster, one of the clamps I had used rusted out and it came loose and got torn to pieces.
Next was a straight pipe dumped out where the stock muffler flange was welded on.
Loved the sound, hated that it rattled everything 5 ways to sunday.
Next was a Cherrybomb Glasspack (3.5"), it was much quieter than the Super 44, I hardly noticed a difference between the glasspack and the stock muffler. No drone.
The cherrybomb came off rather quickly, it was simply too quiet for me.
Next came another straightpipe, this time I threw a 45 degree bend on the pipe, where the flange for the stock muffler was.
Vibrates everything less than the straight dumped exhaust, I was planning on having it exit at the OEM location but the piece of exhaust tubing I had flanged was about 1" too short. No drone at all.
Have yet to get another piece flanged, its been a few weeks but I'll get to it eventually.