The Ko4 is a straight swap over, only difference is the discharge pipe which is interchangeable but to get full benefit you need to change injectors to ed30/s3. I have done nearly 30k on my conversion and the engine is still perfect. Even though the Ko4 engine is stronger it's not really that much stronger. It is well able for a KO4. It really is a great mod for the KO3 engine. The power is there always any rev.