Whenever someone brought me a prefab box, I would always ask them what type of sound they wanted. If they wanted a deeper sound, I would fill it. If they wanted a harder hit, I would leave the fill out. Even with Loaded JL Audio boxes. The sealed ones come with polyfill, so I would take it out of people wanted a harder hit. So yes, poly fill makes a big difference.
I think he & I both prefer the deeper stuff....
I never thought this set-up really even hit very hard though either, strange to say but I think it improved all aspects...
I can definitely feel it more in my back than prior....
This wasnt a prefab...
Kind of bummed with the outcome of the box, but it is what it is. Didnt cost me any more than buying a prefab.
The back wall of the ranger has a 1/2 - 1" inset so the builder used 2 separate sheets offset to mirror the back wall...
He also built the box out of 5/8 MDF instead of 3/4", so the seat wasnt crammed all the way forward....
Needless to say we blew the back of the box apart......
When he repaired it he installed some large pieces of 3/4" bracing on the inside of the rear wall of the box, taking up volume is my concern....
I never played it after the repair without the poly fill,
Once I got the box back I waited for the poly fill to come-in before reinstalling the box,
Regardless if the volume is less now, sounds great with the fill...