"filter=0" does this .. according the google API documentation. Have no reason to suspect it does anything else ...
he <filter> parameter causes Google to filter out some of the results for a given search. This is done to enhance the user experience on Google.com, but for your application, you may prefer to turn filtering off in order to get the full set of search results.
When enabled, filtering takes the following actions:
* Near-Duplicate Content Filter = If multiple search results contain identical titles and snippets, then only one of the documents is returned. * Host Crowding = If multiple results come from the same Web host, then only the first two are returned.