I opted in for the Magnaflow 13749. The case measures 30" long which is identical to the length of the factory muffler, it's just a bit narrower. I haven't installed it yet so I can't speak to how loud it is, however the reason I went for such a large case is because I too don't want an obnoxiously loud exhaust. This one should be just slightly louder than stock, not to mention more free-flowing. It is a staggered 3" in/out so should work nicely with our stock piping.
I'm getting it installed tomorrow so I'll try and grab some before and after video of the sound, and some pics.
'06 WK 4.7L V8 4WD | Recently purchased '05 WK 4.7L V8 4WD