problem extracting and remaking iso file system

[covici]

I found the howto useful, but the question still remains -- why if I just extract the files with NO changes and re make the iso file system -- why is it not the same size? I am running very close to the edge and this is important -- I am already burning 816mb according to cdrdao.

http://www.knoppix.net/docs/index.php/KnoppixRemasteringHowto

That's the guide I used.