yes, adding the pillow stuffing will make your bass a little louder and a little tighter, it will slow down the soundwaves that are coming from your sub. Figure 1llb of stuffing per cubic ft of air space in your box...be sure to staple down the stuffing in layers, wouldnt want it to get into you sub now...
it pretty much makes the box seem larger than it really is..and many people DO use polyfil (same thing as pillow stuffing) the downside is you have to look at the ratings of your sub. if they require 1.0cuft per driver, 1lb of polyfil per sub would work out great. if you have a box thats already 1.15cuft per chamber, theres no need for it. it could distort the sound because its acting like its in too big of a box.
wow, I would have thought putting a fill in the box would make it seem like the box is smaller, I meen, there's "stuff" in it taking up room. But I might try the pillow stuffing, my box is just a teeny bit too small.
haha ya its wierd how it works. but deffinetly, if your box seems a little too small, put about 1 pound of the polyfil in each chamber and it should help you out. goodluck and let us know how it works for ya