I have a nameless axleback on my 3.0R. Sounds alright, but drones on the highway. I now have washers in between y pipe and axleback and it stopped the drone, but it's a half as5 fix: https://www.youtube.com/watch?v=mHRV0XBu4I8
Here is pretty much every exhaust option you can think of for a 3.0R H6:
There has been a lot of discussion about 3.0R exhaust on Legacy Owners Worldwide on facebook. Consensus is to have a loud but drone free 3.0R exhaust, you need a resonator, NOT just an in line muffler thing, but a three foot, dead end T off the midpipe. Google Helmholtz Resonators for info.
AVO and Nameless are the only companies that make Outback specific axlebacks with the correct turn down tips. Any other LGT axleback will fit if you cut your bumper or hang it below the bumper, or get turn down tips welded on.
If you want to go all out, you can get Raptor headers, high flow cats, delete third cat, custom mid pipe to whatever axleback you want, and an XRT tune. Pretty significant power bump.