If you want to get rid of “Removing leading `/’ from member names” being printed to STDERR, but still want to leave off those leading slashes as tar wisely does by default, I saw an excellent solution here by commenter timsoft.

The solution involves using -C option to change directory to the root (/), then specifying the file tree to archive without a leading slash, because now you only need a relative path. This does the same thing as a normal tar create command, but no stripping is needed:

tar fcz bkup.tar.gz -C / home/foo/