I've got it.......scrapped the sub that comes with it.. put in an Infinity Sub. It's a shallow box so not a lot of options for replacements. Also I filled it with "poly fill". It hits good and totally stealth which I like. I don't know if you were kidding but it goes in the space next to spare. Can post pics if you want.
I actually cut out the bottom side of the panel. There are like "fins" that criss cross the bottom side of the panel and I cut those out. I also put Dynamat on the top side of the box it's self to "pad" between the box and the panel. The panel fits pretty snug I get a slight rattle if I'm really pounding it but to be honest you won't even notice it. the bass moves through the car real well and I think because the box sits right on the body.
Now you do have the option to cut out the panel and put the supplied grille in but what I did was install it and did my few modifications to it first then figured if it didn't worj well then I can always cut a hole and put the grille in.
I am extreamly happy with it but if I didn't do the modifications that I had (new sub, poly fill and fittiment) I probably wouldn't be saying that.The fact that it is totally stealth is worth alot to me. I don't live in the greatest neighborhood so the less to attract attention the better.
I will post pics just gotta get my camera back from my gf.