I have the Sub out of my 2013. Want to install the poly Fill. i have removed several screws from the bottom of the box which appeared to hold the speaker in place, however it will not move. There is a screw in the top of the box. I'm pretty sure that screw has to come out, right????

It is really tightly installed, afraid of stripping the head.

 

Yes, that screw on the top also has to come out. But the factory sub is so underpowered, that polyfil is a waste of time.

 

Poly fill is used when a box is smaller than recommended and "fools" the woofer into thinking it has more airspace or to soften some of the tones that sound hollow. Not that there is any intelligence on the woofers part. Port length tunes the box. From what I've read most people that like alot of bass do away with the factory sub for a more efficient and higher output set up. On another note changing the woofer to a higher efficiency woofer can make a big difference too.IE Pulling the sony out and installing a polk audio or other higher quality woofer. Either way Good luck.

 

I just did the poly fill in the Sony Sub on my 14 Raptor last night, after reading about it on another forum. It does make a noticable difference in the bass response and overall sound dynamic (for the better). For $4 worth of polyfill and 10 minutes, it's definitely worth doing.