This is purely my opinion, but weight reduction isn't all it's cracked up to be. I had my old Cavalier's interior gutted to save weight and the noise drove me crazy. I got real tired of hearing EVERYTHING from the smallest of pebbles banging off the wheel wells to the fuel pump's incessant whine, and to every swish of the gas tank...and I think you get the idea.

Now if it's something you don't drive on a regular basis, then by all means and have at it. Strip the interior, take out any unneccessary parts, get lexan instead of your glass, and go crazy with carbon fiber (if you can afford it). Just remember to keep the car balanced weight-wise.