2009 APRILIA Aprilia MXV 4.5, All design solutions on the uncompromising MXV 450 have been dictated by the need to achieve the highest possible level of performance while extending the bike⿿s range of use.The under-seat exhaust, for example, features a brand new path for better motocross performance with more torque at lower revs.Valve gear based on a single overhead cam and four titanium valves per cylinder gives the best possible compromise between compactness, light weight and performance.Thanks to its advanced technology the 45.2 engine is extremely civilised and silent running even in this motocross version, and complies easily with FIM rules for noise emissions (94 dB threshold).