the new GRP engines are identical tot he GRP Ninja......... the new Ninja mills are completely new and off in a different direction......... I do beleive the engine designs were owned by GRP not Ninja....... the new GRP mills have the same case, port count, bore,stroke,carb,rod length,crank bore, crank coating etc....they may have tuned the port timings slightly but for intents and purposes the new GRP engines are just GRP Ninja's with a different cooling head.........they may not have been the best ontroad engines but they are fantastic offroad engines..