All headers are stripped except for Allow, Authorization, Cache-Control, Content-Encoding, Content-Length, Content-Type, Date, Expires, Host, If-Modified-Since, Last-Modified, Location, Pragma, Accept, Accept-Charset, Accept-Encoding, Accept-Language, Content-Language, Mime-Version, Retry-After, Title, Connection, and Proxy-Connection. This is the most "paranoid" option.