Phil,

Thanks for the additional ideas. I've posted a pic below so you can see what the foot box looks like. It's a box as opposed to just a vertical panel. I understand what you are saying about the front wave mixing with the back wave, but the only place that the back wave is leaking out is thru the hole on the top right of the box as you can see in the pic. The rest of it is leaking into the ski locker and into the underfloor chase which I don't think leaks out above the floor. As an FYI, I had a two channel amp that I was running bridged (400wx1) before the Kicker and I had plenty of bass but it was boomy. When I removed the amp, I noticed that I had the bass boost on (+18 db - it was either on or off and I had it on) so maybe that's why it sounded boomy. Mike Mandley from this forum had the same issue and he stuffed his footbox with a loosely folded painter's drop cloth and he said that made the bass tighter so I tried the same thing. The bass does sound tighter now than before but it doesn't have as much volume. Maybe the drop cloth is suffocating the sub.

Part of the reason I am opposed to building an enclosure is that I don't want to suck up the footwell space (and I like the clean look of where it's currently installed) so one option is to go with the Kicker SKM10 marine sub box and woofer. It's got a shallow, but wide box that I think will fit down there without giving up a lot of room and it doesn't involve a lot of cutting. Do you think that will give me the bass I am looking for?

The other easy fix seems to be to buy the right free air sub for the current footbox situation. I think David said JL Audio made the best free air subs by a wide margin so I am hoping he will make a recommendation as to which JL sub I should get.

The third option would be to go thru the effort of completely sealing the footbox properly using a combination of seaboard panels and self expanding foam out of a can to seal the under floor chase and the hole on top.

There is no coaxial speaker on the other side of the footbox.

I will also try swapping the terminals on the sub (actually, I think my head unit has a sub phase switch so I can switch it there).

Thanks,

Al