An 870 will probably be my first purchase after a gun safe.
My bro-in-law has one, and he put the extension mag tube on it, as well as the adjustable stock and pistol grip. Fun to shoot.
He just installed a shorter barrel, too. Can't remember the length (new or original), but it's significantly shorter - legal by 1/4", I think - so whatever the legal length is, his barrel is 1/4" longer than that. Sweet home defense weapon, for sure.