The cyclone add ons have proven to be bogus. Also, your B already has an exhaust gas driven turbo charger which forces extra air into the combustion process.
If you want optimum fuel mileage, make sure the tires have the pressure recommended for maximum load. Then make sure you carry the minimum load - 'no junk in the trunk'. Weight = fuel. Drive moderately. Use cruise control when safe to do so.
Welcome to the forum, you will love the B, and ' good-on-ya'.
PS. This filter might improve power on diesel models:
http://www.knfilters.com/news/news.aspx?ID=525