No matter how you choose to import data, there is a final configuration point within Solr that allows manipulation of the imported data before it gets indexed. The Solr request handlers that update data put documents on an update request processor chain. If you search solrconfig.xml for updateRequestProcessorChain, then you'll see an example.

You can specify which chain to use on the update request with the update.chain parameter. It could be useful, but you'll probably always use one chain. If no chain is specified, you get a default chain of LogUpdateProcessorFactory and RunUpdateProcessorFactory. The following are the possible update request processors that you can choose from. Their names all end in UpdateProcessorFactory.