I have been reading the threads on people placing 6" subs in the passanger footwell area. BUT.....

Has anyone tried to put them behind the the seats, by building MDF panels back there?

 

That would require way too much cutting for me! Take a look behind the plastic panels and you'll see that you're lucky to fit the magnet of a 5-1/4" speaker through the hole, let alone a 6" woofer magnet with MDF surrounding it...

 

can someone who has put a 6" sub in the footwell chime in? how does is sound? how much space does it take up?

 

That would be me. Don't remember exactly where my post is, but do a search on 6W0 and I'm sure you'll come across it pretty easily. It doesn't take up hardly any foot space. There's a hole all the way in the far right corner of the dash that most of the sub will fit up in. I molded the box to come out towards the door just for the added air space and it sounds excellent, considering it's just a 6" sub.