[PHOENIX]

I really need some midrange sound in my setup. I have highs and lows, but not enough midrange. I would like to get some kick panels and put my mids in there.

As far as bass goes I get really good sound and range of bass with my setup even though the speakers are not in the manufacturers suggest air space or box type. My boxes are sealed, which I have found to be much better when the boxes are too small.

Inside the cab, the bass is really good, very strong and clean with no rattles.
From the outside the bass really falls off, which some would consider a good thing. You can definitely hear me coming if I have it pumpin, but it doesn't "carry" the deep bass as far as a car box would. My speakers are designed for larger boxes (more air space) with ports.

There are some rattles from the outside, but nothing even close to a car trunk rattle. I have no complaints about the outside rattle, it is minimal. The rattle I have comes from my drivers door. My hinge pin in worn and the door drops. Because of the pin/latching on that door it creates rattle.

You can buy steel cups that go in the back of the speaker boxes.
These allow you to get a little extra space for the speaker magnet.
You cut a hole in the box the size of the cup and use some sealant and screw the cups in. They are made of steel so they are strong. I don't have pictures of mine, but they has a black, almost baked on finish. I purchased them from my local Circuit City audio install shop. I think they charged me like $10 for the pair. Go to the back and talk with an installer, most of the sales guys will not know what you are talking about.
Because I couldn't find a picture I did up a quick drawing to show what they look like. These cups can be very helpful if you only need a 1/2-3/4" or so.