OK
Stihl MS 880 Magnum 121.6 cc 6.4kW = 8.5825 HP
Stihl MS 660 Magnum 91.6 cc 5.7 kW = 7.6438 HP
Stihl MS 460 Magnum 76.5 cc 4.4 kW = 5.9005 HP
http://www.stihl.com.au/Products/pro...m?iModelID=339
or ask these guys
http://www.arboristsite.com/forumdisplay.php?f=56
a wealth of info and a whole world away from the conventional stuff you see here