Better compression for WAR/EAR files?

Is there a way to better compress WAR files (which is basically a ZIP file containing a lot of other ZIP files, that contain java *.class files)?

ZIP does not exploit inter-file similarities (and is quite old anyway).

Some archivers uncompress files that are compressed with inferior method before archiving them (and restore the old state when unarchiving).

This would be of course for archiving purposes, as application servers expect actual WAR/EAR files.