polyfill in a ported box?

"The gain is in between the 1st and 2nd mark on the amp.

I have been tweaking the HU settings with the  amp's gain set to lowest setting, It is coming along."

You've made a couple references to fiddling with the gain, in a manner which indicates that you are not sure of how to set it.  Get that basic task done correctlly before anything else so you can eliminate it from consideration.

For original question, "Polyfill in a ported box?":  I've done it many times.  Used as a liner by spraying glue and sticking it in small chunks.  You don't want any loose polyfil in there.