Hfssign problem

Hi, I recently started trying to mod my own hfs files, but the problem is every time when i try to hfssign a hfs file, there's always a message that pops up saying "Make your hfs file larger <add comments to text files?>" Is there anyway to fix this problem? And i'm pretty sure my hfs file sizes are the about the same size as normal hfs files. There are maybe 1-5 kb differences between them.