thanks godreborn, but I try to do that.You can do that manually or through the gp4. You may have to replace those files with 0 byte ones.
1. Extract base.pkg file with orbis-pub-cmd
2. Move the Sc0 folder to Image0/sce_sys folder
3. remove the Sc0 folder
4. Use gengp4 for generating the gp4 file for the Image0 folder
5. replace files I want with 0 byte ones
6 Generate the fpkg with orbis-pub-cmd or orbis-pub-gen
My problem is that in certain games i cannot save the current game and in games with updates I cannot remarry the update with the new base pkg.