OK, i've been hearing that if you put cotton fiber, polyester fiber or something along those lines in a sealed box it would sound better, is this true, or is it BS??
Yes actualy it is true some call it poly fill, it tricks the sub into thinking there is more air then there really is. just go to your local fabric store and ask for polyester fill. they use it for stuffing lazy boys and such. its like .50 a foot