I've searched with not much luck for people doing similar installs (maybe I'm using the wrong terms?)...

I am working on installing some small subs and new amps in my roadster. The subs are small enough (8") that I'd like to have them inside the passenger cabin, but large enough that they won't fit in the factory sub locations. Ideally I'd like to avoid any cutting, although it's not out of the question (I had to do some dremel work to get my new tweeters to fit).

My plan, tentatively, is to pull back the carpet on the back wall and insert a sheet of MDF or plywood behind it so I've got something good and solid to mount the amps to without risking the gas tank's integrity. Then I'd like to put the subs underneath the seats.

The questions are:

1. Has anyone gone through the process of pulling back that carpet? Are there any "gotcha"s in the process I need to watch out for?

2. How much space is there under the seats? These subs are free air mountable, but I know they'll sound a little better if I can get them into sealed boxes. I'd prefer to only take the seats out for the install, rather than taking them out to measure and then taking them out again to install. Does anyone have access to any technical drawings or measurements for the space beneath the seats?

3. Does anyone have any particular advice for which direction I should mount the subs? I'm leaning toward downward firing, since low frequencies are omnidirectional anyway. I feel like upward firing might make sitting in the seats a little bit uncomfortable with bass going right up the tailpipe

I'm also up to suggestions if anyone has any other ideas/suggestions. The gas tank is a tough obstacle. If it weren't there, I'd put a box in the trunk with cutouts through to the passenger compartment and mount the amps under the seats, but unfortunately that's not an option. The tight space in the trunk makes it hard to justify building a box back there (although it would be possible with these subs, they only have a 2.5" mounting depth!)

I appreciate any help anyone can offer! I'm about to have a 6 day weekend so I think I'll have plenty of time to do the work to get this stuff all put together while I'm off, and of course I'll post pics when I'm done!