I currently have the OEM Harmon Kardon set up in the car. After reading reviews for a while, I decided to pull the trigger on the BavSound Ghost subwoofers.
The install was very easy. I swapped out the OEM subwoofers, right inside the car and did not have to take out the entire enclosure that holds the speaker. There was more than enough room to work with, under the seat, as to not pull everything out.
The Bavsound subwoofers have a padding that is attached around the entire speaker and looks almost the same size as the OEM padding that is around the speaker. They also send an extra weather strip to put around the speaker, so that the speaker sits tighter. I decided to put the additional weatherstrip on driver side, and install the passenger side without the weather strip, just to try out the difference in sound. Once installed I also noticed that the grille that protects the speaker, actually lays right on top of the speaker, once bolted down. The grille does not touch the OEM speaker. I found this to be very odd. Bavsound confirmed that this is okay.
I put everything back together and decided to listen. As most people have said, the real difference is felt once the volume is above 50%. The speakers are a lot more "Punchy". The Bass has become a lot more clear.
I did notice that the passenger side rattled a lot more than the driver side. I figured that it was due to the fact that I did not add the weatherstrip. I also noticed that the passenger side rattled a bit as well, which I was not too happy with.
The first thing that I thought of doing is ordering dynamat, and adding it under the speakers. I did some research to see if people had good results with this, and for some reason could not find anyone that has added dynamat with the Ghost subwoofers. Most people add the dynamat when they do the Stage One upgrades, but I did not see anyone mention it with the Ghost Subwoofers. I was a bit surprised by this.
I order a few squares of Dynamat and had the chance to install them yesterday. I installed Dynamat inside the car, without removing the enclosure. The difference is very noticeable. The rattling has become a lot less (Especially due to the fact that I added the weatherstrip on passenger side), and the bass has become even louder. I am now very happy with the subwoofers. My suggestion to anyone that is going to be installing these speakers, is to also install the Dynamat.
The only issue I have now, is that when the music goes above 75%, the regular speakers start to lose quality while the Ghost Subwoofers start to actually wake up and sound even better. I guess I will have to do the Stage One Speaker Upgrade, to make sure that the regular speakers can hold quality at higher volumes.
