rynogee wrote:ok, thanks, I'm not completely sure what I do or don't need yet. I just went in to an installer for a quote/look into doing the box for me and am not 100% sure where I'll go with it.
If you go stick with the stock 8" sub size, all you'll need is a maximum of 3 Subaru parts and no custom work to physically make it fit. That'll be pretty cheap - under $200 for everything including the Sub (plus an inexpensive Amp if you don't already have one).
*If you can remove your right-hand storage bin to make it look like the last picture in this post, all you'll need is the Metal Sub Plate and a Grille. If you can't, you'll need need the whole side boot trim as well.*
And as long as you avoid the weak McIntosh sub and buy a decent eg Polk (ask Ben, he still has his), it'll sound good. Only people like me spend crazy $s to go to up to a 10". Then do you need to get a Box/Enclosure made like the ones in this thread. That gets $$s, plus more $s for a bigger sub, and a bigger amp.
I wish I knew the Outbacks (or even standard Liberties) better, but if you post a pic of your boot we can work it out.
To give you an idea, this is what the Factory Sub enclosure looks like (sorry for the terrible picture, it is all I could find):
This is what the sub grille looks like (clips just pull off):
Underneath it looks like this. The meal plate I posted earlier screws into the factory holes that I think every Outback/Liberty will have. So it should be a straight fit:
With the metal plate unscrewed (this is probably what yours looks like - minus the sound insulation styrofoam. Only the McInstosh cars would have the sub plate):