I have one and its an awsome engine, there is more there than meets the eye. First, its rear exhaust and possibly more efficient than a side exhaust. Secondthe sleeve is similar to the OS .30vg, in that it uses a bi-metal cylinder coating, It uses a nickel over silicone layering to help it last longer thanplain nickel layer. Personally i think its a better .12 than the old cv, if not in HP, its got better torque and smoother powerband