Ive used dynamat as well but tried 5x5 directly on the back of 15 Ultra speaker pods to get the effect I needed.
I tried polyfil inside my pods but it really didn't do what I wanted. I've since figured out I probaby didn't use enough. After I install my amp later this week I ay try poly again. Depending on your speakers and fairing ymmv with polyfill but at least it's cheap.

It's just a guess but I think that those that wrap a layer or 2 around their magnet may be just isolating reverb from between the speaker and the outer fairing which is still a plus but not really what polyfill is supposed to do.

In other speaker enclosures the fill can be poly, fiberglass or long hair wool or acoustic foam blocks. Poly is cheap and easy to use but they all essentially do the same thing in that they change the volume of the box. The intent is to make the speaker think the box is bigger than it is. It doesn't change the breathability but how the air inside is used. There is also the benefit of absorbing some of the waves that bounce around inside the enclosure as well. If you have the right amount of fill, the fibers will begin to wiggle and change the sound wave to a thermodynamic wave to create a heat transfer and make the air inside less dense. As with anything though you can have too much or too little fill, too much fill can cause damage to the speaker though. In car audio rule of thumb is 16-24 ounces per cubic foot up to 3 cubic enlosure that is not the sheet type of fill but the loose stuff used in pillows and pulled or stretched. Densely packed fill will reverse the effect.

Since this is motorcycle audio we still need to experiment a little and it could be that with some speakers with no pods in the fairing will need the denser pack poly to reduce volume or isolate and others will need loose fill in a pod to increase and others will be just fine without any fill. It all depends on what sounds best to each rider. What sounds amazing to me may not be what you like.

 

double post