Does anyone have a sub box in the attic space of the trunk? If so what size subs and box fits snug with the spare tire and stock sub removed? A quick measurement seems like 12" H x 32" W x 16" D should be about right? So Id assume either three 8s (1.3 cubes each / or two 8s ported), two 10s or 12s sealed in 1.7 cubes each. I assumed not enough volume to port it properly for any decent larger sub. Two 15s would be a stretch.

I know from experience our cars dont like rear firing subs so I assumed a box that fit snug in the attic firing up would be the most efficient and least obtrusive.

Ive already swapped out my stock sub for a JL w3 and at first it seemed ok but now that I have a dedicated midrange it leaves a LOT to be desired.

Full setup is a cheap pioneer deck, cheap JBL 6.5 components up front in the doors on a cheap pioneer 400w amp and a cheap self powered rockville 12" sub on dedicated midrange duty under the drivers seat. The 6.5" JL sub is not even audible now. Literally turning it on and off makes no audible difference.