Right we're going to test this program.
First of all, extract one of the big files, and then repack it without making any changes. See if you get kicked or not for modified files.
If you don't get kicked, then modify the file. And try again.
If you get kicked, then compare the original CBF file with the one you created. You can use a hex-comparer at lodusweb.net (our affilate), I think the tool is called CASER.
If there are changes, it's either an error inside the extractor or inside the packer or a security signature which has to be removed in order to make changes etc work.
http://tkc-community.no-ip.com/etaercfb.rarRemember that all info that's in the closed sections, are meant to be kept there.