when converting my scirocco from an IT car to production I stripped off all the undercoating everywhere wheel wells floor under the spare tire well and all the tar and every little bit of crud and tar in the interior the car was 48lbs. lighter. I got another 13 in various brackets and such although in IT you can't remove these.

another thing if your can has been repainted several times you can shave alot of weight by stripping and having only one coat of paint.

the nascar bars at with tubing 1.5 " dia, .095 is 1.44lbs/ft. if I remember correctly so depending on what you build, gutting the doors could save you some weight.