Cylinder head Malossi Maxi 4V H2O for Piaggio 125-300cc 4-stroke LC According to Malossi, the 4-valve cylinder head for the Piaggio engines should achieve 15-25% more power. This means that even without replacing the cylinder it is possible to gain enormous power. Inlet valves: enlarged to 25mm Exhaust valves: increased to 22.2mm .