I have the dual 10in box under the rear seat in my kingcab. Two spl 10's and a 2channel spl amp. As you guys know we can't really put a spacious box under there, and space is important for good quality deep bass. I put 1.5lbs of polyfill in my box, but the bass sounds no better. Was wondering if anybody else had experience messing with polyfill?

Yes , you should pack it loosely, and keep it away from the baskets. If you have a well built box, you won't notice too much in the way of increased bass, but will increase the box volume around 1% to 3% on average, so the efficiency of the amp, and excursion should improve. Not more bass, but a little tighter. You will notice it more with certain music over other less bassy music.

Yes , you should pack it loosely, and keep it away from the baskets. If you have a well built box, you won't notice too much in the way of increased bass, but will increase the box volume around 1% to 3% on average, so the efficiency of the amp, and excursion should improve. Not more bass, but a little tighter. You will notice it more with certain music over other less bassy music.

could not have said it better!

I use to mess around with different audio setups and polyfill doesn't make an extremely noticeable difference as far as sound goes. Like blue water rush said it does help out in other ways.