I havent really got anything to add to taking stuff out, but a few questions.
Not so much why take it all out, as that is fairly obvious. But HOW much difference does it make. I was once told every 200kgs = about 30hp, but no one ever mentioned how much difference it made to handeling, and braking distances etc. Going by the 200kgs = 30hp thing changing all the bolts etc would actually seem cheap to some power mods.
But! While I think about it, Im not 100% sure on what you can rip out, but say light globes? wiring to those globes etc? If you dont need it, get rid of it.