We have developed O.S.SPEED R21 Shimo edition collaborated with Takaaki Shimo, a multiple podium winner of the IFMAR 1/8 Racing World Championship. It is a 7-port engine with a new cylinder liner, which has extra holes to reduce overheating. The cooling head and 8.5mm carburetor restrictor are anodized in the special color; champagne gold. The crankshaft is modified to meet his preference, smooth power transition from bottom to the top speed. For the first time we make the combination of TR02 (EFRA2165) silencer with MR03-WC manifold to dedicate to this special edition.