The Winegard HD6055P is advertised to have 7.0 to 8.6 dB forward gain and 18 to 20 dB F/B.
http://www.winegarddirect.com/pdf/spec_HD6055P.pdf
The Antennacraft FM6 specs are less specific, simply claiming forward gain of 6.6 dB and 18.9 dB F/B.
http://www.antennacraft.net/pdfs/FM6.pdf
Then there's the Wade C & J Series.
http://www.wadeantenna.com/Wade/CSeries.pdf http://www.wadeantenna.com/Wade/jseriesyagi.pdf