Thanks again for the advice. This is constructive criticism as I am learning as I go.
I just assumed I needed a port as the box was rather small. Perhaps I will try plugging the port to see if the sound improves.
The amp is the MP500. I did not add any other speakers aside from the sub (the car is a base and only has front components) however I did run wire to the rear stock woofer location and a second set of rca cables to the back just in case I decide to add them.
Regarding the mat it was free (left over from a friends project. My biggest reasoning for this was to eliminate the squeaks from the plastic bits. It turns out these were mostly coming from the plastic push connectors from the plastic rear walls. I ended up felting all the holes and anywhere plastic touched other plastic.

What is better about the s or r types?
Is the sound quality vary enough to justify converting.