The Ducati Monster remained relatively unchanged until 2000, when Ducati added fuel injection to the M900 model. Perhaps more importantly, in 2001 Ducati also introduced the S4, which added the liquid-cooled four-valve Superbike engine to the stable. Other technical changes that year included semi-floating front disc brakes with Brembo four-piston calipers, lighter Brembo wheels as well as 43 mm Showa inverted forks. 2002 saw the introduction of the limited, 300 edition, high-spec, S4 Fogarty.
In November 2005, a new top of the range model was announced: the S4RS Testastretta. This new model uses the engine from the 999 Superbike with Öhlins suspension front and rear and radial front brakes. Also in 2005, Ducati added the S2R Desmodue (two-valved Desmodromic engine) line to the Monster family: styled akin to the four-valve S4R, but with the simpler two-valve 800 cc and 1,000 cc motors in the S2R 800 and S2R 1000, respectively. February 2006 marked the announcement of the 2007 Monster 695. It replaced the Monster 620 and was introduced June 2006.
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