I'm currently looking for a Subaru brand OEM underseat subwoofer. Interested in Non-oem for the right price.
Update: Found one at SubaruGenuineParts.com and installed myself in about an hour without any special tools. Due to all the negative comments my expectations were low but it sounds great. Much more of a well rounded stock sound system now. I would recommend it to those who don't need window rattling bass.