I would have to think that the carpet and mat must block some of the sound from the sub, but it sounds clean and clear to me. When I first installed it my intention was to listen to it with and without the mat, but it sounded so good that I didn't try it without the mat. As a matter of fact...
They are a little tricky to make but not impossible. I used 3/4 inch PVC board, but MDF would work fine. I removed the oem shelf floor and made upright supports that used the existing mounting points for the rear panels. When you remove the shelf ( they just pop out) you will see what i mean...
I think everyone feels the same regarding the sound system in the Z. However, it can amazing without spending too much if you are willing to do the work yourself. It took me a little trial and error to get it right. Even after replacing the rear speakers I was still underwhelmed with the...