ScriptedImporter question

Hi All
I have a scriptedimporter that during the import of fbx files removes a lot of unwanted objects and meshes, the fbx files can have 100,000’s of objects in that arn’t needed in Unity. So the custom importer removes all the data and works fine and when I add the object to the scene it is just the objects I need, my question is when i build the project is the entire orginal FBX file included in the build with all the unneeded data or does just the striped down data in the final prefab get included?

Unity only induces what is referenced. (except for the resources folder and streaming assets)
If you only reference some of a imported models meshes unity will unity include the referenced once.