Getting ready to build my sub box. Sub needs .80 cuft of space. I'd like to put it behind the back seat but can't get a box that big in there. It's been a long time since I've used polyfill but would it be possible to put enough poly inside an 18x12x6.5 box to fool the sub into thinking it's got .80cuft or should I just suck it up and mount the sub in the trunk? It's a JL 12tw3 powered by an alpine mrv-m500. Thank you.

 

You can't go wrong using under strut sub box if you are willing to sacrifice some trunk space. Zenclosure builds very affordable ones. They fit perfect. Building your own is not a bad idea either.

 

Based on those dimensions the box is already .82 cu ft.However the golden rule I have always used is 1lb of poly per cu ft, this makes the box appear to be 25% larger. Reference: http://nousaine.com/nousaine_tech_articles.html

If you want to go behind the seats (stock Bose location) then a glove box is the way to go. I tired that with a Polk MM 12" but couldn't stand the rattles thus I'm switching to a JL 10" in a corner box. As mentioned the under the strut tower is the easiest/best if you can deal with losing that space.

 

I've decided to yank the spare and drop it in there. Plenty of room. Thank you though.