I'd say so. Sounds better to me.
The polyfill makes the sub think it's in a bigger box than it really is by slowing down sound waves. Folks been using that for years to gain airspace in sealed enclosures. Don't pack it, should be loose like a pillow.
The sound deadening on the sub box reduces vibrations of the cheap plastic box. There's a reason we build boxes out of 3/4" mdf
.
The sound deadening throughout the inside of the vehicle cuts down on noise and vibrations that cancel out your music. It has made a huge difference in both road noise and sound quality in mine.... and even helps with the drone/vibrations from the mds/eco.
The only downside to this, is it's a **** ton of work/time to do.
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